Determining if the C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx exist failed with the following output:
Change Dir: C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp

Run Build Command:"C:/msys64/usr/bin/make.exe" "cmTC_ece6c/fast"
/usr/bin/make -f CMakeFiles/cmTC_ece6c.dir/build.make CMakeFiles/cmTC_ece6c.dir/build
make[1]: Entering directory '/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_ece6c.dir/CheckSymbolExists.c.obj

/C/msys64/mingw32/bin/gcc.exe   -march=i686 -mtune=generic -O2 -pipe    -o CMakeFiles/cmTC_ece6c.dir/CheckSymbolExists.c.obj   -c /C/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.c
C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.c:2:10: fatal error: strcasecmp: No such file or directory

 #include <strcasecmp>

          ^~~~~~~~~~~~

compilation terminated.

make[1]: *** [CMakeFiles/cmTC_ece6c.dir/build.make:66: CMakeFiles/cmTC_ece6c.dir/CheckSymbolExists.c.obj] Error 1
make[1]: Leaving directory '/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp'
make: *** [Makefile:126: cmTC_ece6c/fast] Error 2

File C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include <strcasecmp>

int main(int argc, char** argv)
{
  (void)argv;
#ifndef C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx
  return ((int*)(&C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx))[argc];
#else
  (void)argc;
  return 0;
#endif
}

Determining if the C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx exist failed with the following output:
Change Dir: C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp

Run Build Command:"C:/msys64/usr/bin/make.exe" "cmTC_fde93/fast"
/usr/bin/make -f CMakeFiles/cmTC_fde93.dir/build.make CMakeFiles/cmTC_fde93.dir/build
make[1]: Entering directory '/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_fde93.dir/CheckSymbolExists.c.obj

/C/msys64/mingw32/bin/gcc.exe   -march=i686 -mtune=generic -O2 -pipe    -o CMakeFiles/cmTC_fde93.dir/CheckSymbolExists.c.obj   -c /C/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.c
C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.c:2:10: fatal error: asinh: No such file or directory

 #include <asinh>

          ^~~~~~~

compilation terminated.

make[1]: *** [CMakeFiles/cmTC_fde93.dir/build.make:66: CMakeFiles/cmTC_fde93.dir/CheckSymbolExists.c.obj] Error 1
make[1]: Leaving directory '/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp'
make: *** [Makefile:126: cmTC_fde93/fast] Error 2

File C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include <asinh>

int main(int argc, char** argv)
{
  (void)argv;
#ifndef C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx
  return ((int*)(&C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx))[argc];
#else
  (void)argc;
  return 0;
#endif
}

Determining if the function clock_gettime exists in the rt failed with the following output:
Change Dir: C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp

Run Build Command:"C:/msys64/usr/bin/make.exe" "cmTC_2bb84/fast"
/usr/bin/make -f CMakeFiles/cmTC_2bb84.dir/build.make CMakeFiles/cmTC_2bb84.dir/build
make[1]: Entering directory '/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_2bb84.dir/CheckFunctionExists.c.obj

/C/msys64/mingw32/bin/gcc.exe   -march=i686 -mtune=generic -O2 -pipe -DCHECK_FUNCTION_EXISTS=clock_gettime   -o CMakeFiles/cmTC_2bb84.dir/CheckFunctionExists.c.obj   -c /C/msys64/mingw32/share/cmake-3.10/Modules/CheckFunctionExists.c
Linking C executable cmTC_2bb84.exe

/C/msys64/mingw32/bin/cmake.exe -E remove -f CMakeFiles/cmTC_2bb84.dir/objects.a
/C/msys64/mingw32/bin/ar.exe cr CMakeFiles/cmTC_2bb84.dir/objects.a "CMakeFiles/cmTC_2bb84.dir/CheckFunctionExists.c.obj" 
/C/msys64/mingw32/bin/gcc.exe -march=i686 -mtune=generic -O2 -pipe -DCHECK_FUNCTION_EXISTS=clock_gettime  -pipe  -Wl,--whole-archive CMakeFiles/cmTC_2bb84.dir/objects.a -Wl,--no-whole-archive  -o cmTC_2bb84.exe -Wl,--major-image-version,0,--minor-image-version,0 -lrt -lkernel32 -luser32 -lgdi32 -lwinspool -lshell32 -lole32 -loleaut32 -luuid -lcomdlg32 -ladvapi32 
C:/msys64/mingw32/bin/../lib/gcc/i686-w64-mingw32/7.3.0/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lrt

collect2.exe: error: ld returned 1 exit status

make[1]: *** [CMakeFiles/cmTC_2bb84.dir/build.make:99: cmTC_2bb84.exe] Error 1
make[1]: Leaving directory '/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp'
make: *** [Makefile:126: cmTC_2bb84/fast] Error 2


Determining if the getc_unlocked exist failed with the following output:
Change Dir: C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp

Run Build Command:"C:/msys64/usr/bin/make.exe" "cmTC_6a36b/fast"
/usr/bin/make -f CMakeFiles/cmTC_6a36b.dir/build.make CMakeFiles/cmTC_6a36b.dir/build
make[1]: Entering directory '/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_6a36b.dir/CheckSymbolExists.c.obj

/C/msys64/mingw32/bin/gcc.exe   -march=i686 -mtune=generic -O2 -pipe    -o CMakeFiles/cmTC_6a36b.dir/CheckSymbolExists.c.obj   -c /C/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.c
C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.c: In function 'main':

C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.c:8:19: error: 'getc_unlocked' undeclared (first use in this function); did you mean '_getc_nolock'?

   return ((int*)(&getc_unlocked))[argc];

                   ^~~~~~~~~~~~~

                   _getc_nolock

C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.c:8:19: note: each undeclared identifier is reported only once for each function it appears in

make[1]: *** [CMakeFiles/cmTC_6a36b.dir/build.make:66: CMakeFiles/cmTC_6a36b.dir/CheckSymbolExists.c.obj] Error 1
make[1]: Leaving directory '/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp'
make: *** [Makefile:126: cmTC_6a36b/fast] Error 2

File C:/msys64/home/BrianP/src/MINGW-packages/mingw-w64-kicad-git/src/build-i686-w64-mingw32/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include <stdio.h>

int main(int argc, char** argv)
{
  (void)argv;
#ifndef getc_unlocked
  return ((int*)(&getc_unlocked))[argc];
#else
  (void)argc;
  return 0;
#endif
}