Avoid the risk of a false positive detection of MSG_NOSIGNAL when cross compiling a Windows target.

acinclude.m4

@@ -913,11 +913,26 @@ AC_DEFUN([CURL_CHECK_MSG_NOSIGNAL], [
   AC_CACHE_CHECK([for MSG_NOSIGNAL], [ac_cv_msg_nosignal], [
     AC_COMPILE_IFELSE([
       AC_LANG_PROGRAM([
+#undef inline 
+#ifdef HAVE_WINDOWS_H
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+#include <windows.h>
+#ifdef HAVE_WINSOCK2_H
+#include <winsock2.h>
+#else
+#ifdef HAVE_WINSOCK_H
+#include <winsock.h>
+#endif
+#endif
+#else
 #ifdef HAVE_SYS_TYPES_H
 #include <sys/types.h>
 #endif
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
+#endif
 #endif
       ],[
         int flag=MSG_NOSIGNAL;