workaround for building with mingw32

source/blender/blenlib/intern/winstuff.c

@@ -153,6 +153,8 @@ void RegisterBlendExtension(void)
 	GetSystemDirectory(SysDir, FILE_MAXDIR);
 #ifdef WIN64
 	ThumbHandlerDLL = "BlendThumb64.dll";
+#elif defined(__MINGW32__)
+	ThumbHandlerDLL = "BlendThumb.dll";
 #else
 	IsWow64Process(GetCurrentProcess(), &IsWOW64);
 	if (IsWOW64 == TRUE)