SBCL 1.2.15 does not compile under Cygwin

[Krystian Bacławski]

I'm trying to compile SBCL 1.2.15 under Cygwin. I downloaded SBCL 1.2.15 binary for Windows x86 and installed under Windows 7 32-bit. During SBCL's runtime compilation (make.sh) I encountered plenty of errors, mainly regarding conflicts between definitions:

[...]
In file included from /usr/include/sys/time.h:49:0,
                 from win32-os.h:24,
                 from target-os.h:1,
                 from os.h:41,
                 from alloc.c:22:
/usr/include/sys/select.h:31:5: error: conflicting types for 'select'
 int select __P ((int __n, fd_set *__readfds, fd_set *__writefds,
     ^
In file included from win32-os.h:17:0,
                 from target-os.h:1,
                 from os.h:41,
                 from alloc.c:22:
/usr/include/w32api/winsock2.h:995:34: note: previous declaration of 'select' was here
   WINSOCK_API_LINKAGE int WSAAPI select(int nfds,fd_set *readfds,fd_set *writefds,fd_set *exceptfds,const PTIMEVAL timeout);
                                  ^
In file included from gc-internal.h:20:0,
                 from alloc.h:17,
                 from alloc.c:23:
thread.h:258:0: warning: "SIGSTKSZ" redefined
 #define SIGSTKSZ 1024
 ^
In file included from /usr/include/sys/signal.h:113:0,
                 from /usr/include/signal.h:5,
                 from /usr/include/time.h:152,
                 from pthreads_win32.h:4,
                 from runtime.h:19,
                 from alloc.c:21:
/usr/include/cygwin/signal.h:361:0: note: this is the location of the previous definition
 #define SIGSTKSZ 32768
 ^
<builtin>: recipe for target 'alloc.o' failed
make: *** [alloc.o] Error 1

$ uname -a
CYGWIN_NT-6.1 Windows7 2.2.1(0.289/5/3) 2015-08-20 11:40 i686 Cygwin

I'm trying to compile SBCL because it's a crucial dependency of FriCAS (fricas.sf.net). FriCAS will not run without Cygwin environment. So far we used CLISP, but the version provided in Cygwin distribution seems to be broken currently. SBCL is our choice for FriCAS under Linux and MacOSX. We'd prefer to use SBCL on all supported platforms.

[Stas Boukarev (stassats)]

I'm not interested in the cygwin build working, but will happily accept a patch.