Win32: stdint.h used for MinGW GCC.

There is no need to restrict stdint.h only to MinGW-w64 GCC, it is
available with MinGW GCC as well.

src/os/win32/ngx_win32_config.h

diff --git a/src/os/win32/ngx_win32_config.h b/src/os/win32/ngx_win32_config.h
index 7f73e07..fa5aea3 100644
--- a/src/os/win32/ngx_win32_config.h
+++ b/src/os/win32/ngx_win32_config.h
@@ -58,7 +58,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
-#ifdef __MINGW64_VERSION_MAJOR
+#ifdef __GNUC__
 #include <stdint.h>
 #endif
 #include <ctype.h>