MinGW 32 build broken for gcc 4.8.1

[Ralph Lange]

The EPICS 3.15 build using 32bit MinGW on Windows (mingw32-gcc-4.8.1-4) is broken.

[...]
gcc -DDONT_USE_POSIX_THREAD_PRIORITY_SCHEDULING -D_MINGW -O3 -Wall -m32 -DEPICS_BUILD_DLL -DEPICS_CALL_DLL -I. -I../O.Common -I. -I../../../src/libCom/osi/compiler/gcc -I../../../src/libCom/osi/compiler/default -I. -I../../../src/libCom/osi/os/WIN32 -I../../../src/libCom/osi/os/default -I.. -I../../../src/libCom/as -I../../../src/libCom/bucketLib -I../../../src/libCom/calc -I../../../src/libCom/cvtFast -I../../../src/libCom/cppStd -I../../../src/libCom/cxxTemplates -I../../../src/libCom/dbmf -I../../../src/libCom/ellLib -I../../../src/libCom/env -I../../../src/libCom/error -I../../../src/libCom/fdmgr -I../../../src/libCom/flex -I../../../src/libCom/freeList -I../../../src/libCom/gpHash -I../../../src/libCom/iocsh -I../../../src/libCom/log -I../../../src/libCom/macLib -I../../../src/libCom/misc -I../../../src/libCom/osi -I../../../src/libCom/ring -I../../../src/libCom/taskwd -I../../../src/libCom/timer -I../../../src/libCom/yacc -I../../../src/libCom/yacc -I../../../src/libCom/yajl -I../../../include/compiler/gcc -I../../../include/os/WIN32 -I../../../include -o osdThread.obj -c ../../../src/libCom/osi/os/WIN32/osdThread.c
../../../src/libCom/osi/os/WIN32/osdThread.c:100:13: error: conflicting types for 'DllMain'
 BOOL WINAPI DllMain (
             ^
In file included from c:\mingw\include\windows.h:62:0,
                 from ../../../src/libCom/osi/os/WIN32/osdThread.c:28:
c:\mingw\include\winbase.h:1051:13: note: previous declaration of 'DllMain' was here
 BOOL WINAPI DllMain(HINSTANCE, DWORD, LPVOID);
             ^
../../../configure/RULES_BUILD:219: recipe for target 'osdThread.obj' failed
mingw32-make[3]: *** [osdThread.obj] Error 1
mingw32-make[3]: Leaving directory 'C:/Users/langer/Documents/Work/EPICS/V3/3.15/fix-nan-inf-updates/src/libCom/O.win32-x86-mingw'

This was first reported by Anindya Roy <email address hidden> on Tech-Talk back in February.
http://www.aps.anl.gov/epics/tech-talk/2014/msg00313.php

[Ralph Lange (ralph-lange)]

The attached patch fixes the issue.

Careful, though:
I have no idea what kind of #ifdef'ization this fix might need to be portable across Windows version and compilers.

[Ralph Lange (ralph-lange)]

Fix does work on Windows7 for MinGW (32bit) and MSVC 12.0 (Visual Studio 2013) (32bit and 64bit)

[Andrew Johnson (anj)]

Doesn't break my MinGW or MSVS 2010 builds, so please apply.