[glib] gwin32: Fix detection of MinGW32 vs MinGW-w64

[Philip Withnall <pwithnall src gnome org>]

commit a9fe62aa2cfcf3fb3c8223f31ccb8936784c85eb
Author: Nirbheek Chauhan <nirbheek centricular com>
Date:   Sun May 6 15:29:09 2018 +0530

    gwin32: Fix detection of MinGW32 vs MinGW-w64
    
    __MINGW32__ is defined on all MinGW variants including MinGW-w64.
    __MINGW64_VERSION_MAJOR is only defined on MinGW-w64.
    
    This difference is important because on MinGW-w64 we must #include
    winternl.h because including ntdef.h results in compiler errors
    about symbol redefinition, and the header warns that it is deprecated
    and may be removed in the future.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=795849

 glib/gwin32.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/glib/gwin32.c b/glib/gwin32.c
index cc6da5f99..a176514b1 100644
--- a/glib/gwin32.c
+++ b/glib/gwin32.c
@@ -59,8 +59,8 @@
 #ifdef _MSC_VER
 #pragma comment (lib, "ntoskrnl.lib")
 #endif
-#elif defined (__MINGW32__)
-/* mingw-w64, not MinGW, has winternl.h */
+#elif defined(__MINGW32__) && !defined(__MINGW64_VERSION_MAJOR)
+/* mingw-w64 must use winternl.h, but not MinGW */
 #include <ntdef.h>
 #else
 #include <winternl.h>