Fix compilation with MinGW runtime 3.22.2 and w32api 3.18.2

* nt/inc/ms-w32.h (_WIN32_WINNT) [!MINGW_W64]: Undefine before
defining to avoid redefinition warnings.

* nt/inc/sys/stat.h (_SYS_STAT_H, _INC_STAT_H): Define, to avoid
inclusion of sys/stat.h from the system headers, which could then
lead to compilation errors due to redefinition of 'struct stat'
etc.  This is needed because latest versions of MinGW runtime
include sys/stat.h from wchar.h.

* src/image.c (__MINGW_MAJOR_VERSION) [WINDOWSNT]: Temporarily
redefine to 4 to avoid conflict between 2 definitions of
MemoryBarrier.  (Bug#24613)

Do not merge to master!

2 files changed, 9 insertions, 0 deletions

diff --git a/nt/inc/ms-w32.h b/nt/inc/ms-w32.h
index d1534336c49..b4eb5622242 100644
--- a/nt/inc/ms-w32.h
+++ b/nt/inc/ms-w32.h
@@ -146,6 +146,7 @@ extern char *getenv ();
    in its system headers, and is not really compatible with values
    lower than 0x0500, so leave it alone.  */
 #ifndef MINGW_W64
+# undef _WIN32_WINNT
 # define _WIN32_WINNT 0x0400
 #endif
 
diff --git a/nt/inc/sys/stat.h b/nt/inc/sys/stat.h
index 45bc2ea1e0c..ea14f075471 100644
--- a/nt/inc/sys/stat.h
+++ b/nt/inc/sys/stat.h
@@ -30,6 +30,14 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 # define __MINGW_NOTHROW
 #endif
 
+/* Prevent the MinGW stat.h header from being included, ever.  */
+#ifndef _SYS_STAT_H
+# define _SYS_STAT_H
+#endif
+#ifndef _INC_STAT_H
+# define _INC_STAT_H
+#endif
+
 #include <sys/types.h>
 #include <time.h>