winsup: disable fortify source

winsup: disable fortify source

When using a compiler that automatically enables -D_FORTIFY_SOURCE,
building winsup fails with errors like below.  Since winsup is not
setup to compile itself with _FORTIFY_SOURCE, disable it for now.

make[4]: Entering directory '.../x86_64-pc-cygwin/winsup/cygwin'
  CC       libc/minires-os-if.o
In file included from .../newlib/newlib/libc/include/ssp/strings.h:34,
                 from .../newlib/newlib/libc/include/strings.h:77,
                 from .../newlib/newlib/libc/include/string.h:24,
                 from ../../../../../winsup/cygwin/string.h:12,
                 from /usr/x86_64-pc-cygwin/usr/include/w32api/guiddef.h:154,
                 from /usr/x86_64-pc-cygwin/usr/include/w32api/winnt.h:635,
                 from /usr/x86_64-pc-cygwin/usr/include/w32api/minwindef.h:163,
                 from /usr/x86_64-pc-cygwin/usr/include/w32api/windef.h:9,
                 from /usr/x86_64-pc-cygwin/usr/include/windows.h:69,
                 from ../../../../../winsup/cygwin/winlean.h:56,
                 from ../../../../../winsup/cygwin/winsup.h:84,
                 from ../../../../../winsup/cygwin/libc/minires-os-if.c:13:
.../newlib/winsup/cygwin/include/ssp/socket.h:9:1: error: conflicting types for 'recv';
  have 'ssize_t(int,  void *, size_t,  int)' {aka 'long int(int,  void *, long unsigned int,  int)'}
    9 | __ssp_redirect0(ssize_t, recv, \
      | ^~~~~~~~~~~~~~~
In file included from /usr/x86_64-pc-cygwin/usr/include/w32api/ws2tcpip.h:17,
                 from ../../../../../winsup/cygwin/libc/minires-os-if.c:14:
/usr/x86_64-pc-cygwin/usr/include/w32api/winsock2.h:1022:34: note: previous declaration of 'recv' with
  type 'int(SOCKET,  char *, int,  int)' {aka 'int(long long unsigned int,  char *, int,  int)'}
 1022 |   WINSOCK_API_LINKAGE int WSAAPI recv(SOCKET s,char *buf,int len,int flags);
      |                                  ^~~~
In file included from .../newlib/newlib/libc/include/ssp/strings.h:34,
                 from .../newlib/newlib/libc/include/strings.h:77,
                 from .../newlib/newlib/libc/include/string.h:24,
                 from ../../../../../winsup/cygwin/string.h:12,
                 from /usr/x86_64-pc-cygwin/usr/include/w32api/guiddef.h:154,
                 from /usr/x86_64-pc-cygwin/usr/include/w32api/winnt.h:635,
                 from /usr/x86_64-pc-cygwin/usr/include/w32api/minwindef.h:163,
                 from /usr/x86_64-pc-cygwin/usr/include/w32api/windef.h:9,
                 from /usr/x86_64-pc-cygwin/usr/include/windows.h:69,
                 from ../../../../../winsup/cygwin/winlean.h:56,
                 from ../../../../../winsup/cygwin/winsup.h:84,
                 from ../../../../../winsup/cygwin/libc/minires-os-if.c:13:
.../newlib/winsup/cygwin/include/ssp/socket.h:13:1: error: conflicting types for 'recvfrom';
  have 'ssize_t(int,  void *, size_t,  int,  struct sockaddr *, socklen_t *)' {aka 'long int(int,  void *, long unsigned int,  int,  struct sockaddr *, int *)'}
   13 | __ssp_redirect0(ssize_t, recvfrom, \
      | ^~~~~~~~~~~~~~~
In file included from /usr/x86_64-pc-cygwin/usr/include/w32api/ws2tcpip.h:17,
                 from ../../../../../winsup/cygwin/libc/minires-os-if.c:14:
/usr/x86_64-pc-cygwin/usr/include/w32api/winsock2.h:1023:34: note: previous declaration of 'recvfrom' with
  type 'int(SOCKET,  char *, int,  int,  struct sockaddr *, int *)' {aka 'int(long long unsigned int,  char *, int,  int,  struct sockaddr *, int *)'}
 1023 |   WINSOCK_API_LINKAGE int WSAAPI recvfrom(SOCKET s,char *buf,int len,int flags,struct sockaddr *from,int *fromlen);
      |                                  ^~~~~~~~
make[4]: *** [Makefile:1930: libc/minires-os-if.o] Error 1
  CC       gmon.o
../../../../../winsup/cygwin/gmon.c:60: error: "bzero" redefined [-Werror]
   60 | #define bzero(ptr,size) memset (ptr, 0, size);
      |
In file included from .../newlib/newlib/libc/include/strings.h:77,
                 from .../newlib/newlib/libc/include/string.h:24,
                 from ../../../../../winsup/cygwin/string.h:12,
                 from /usr/x86_64-pc-cygwin/usr/include/w32api/guiddef.h:154,
                 from /usr/x86_64-pc-cygwin/usr/include/w32api/winnt.h:635,
                 from /usr/x86_64-pc-cygwin/usr/include/w32api/minwindef.h:163,
                 from /usr/x86_64-pc-cygwin/usr/include/w32api/windef.h:9,
                 from /usr/x86_64-pc-cygwin/usr/include/windows.h:69,
                 from ../../../../../winsup/cygwin/winlean.h:56,
                 from ../../../../../winsup/cygwin/winsup.h:84,
                 from ../../../../../winsup/cygwin/gmon.h:69,
                 from ../../../../../winsup/cygwin/gmon.c:47:
.../newlib/newlib/libc/include/ssp/strings.h:43: note: this is the location of the previous definition
   43 | #define bzero(dst, len) \
      |
cc1: all warnings being treated as errors