Don't use msvc_compat's C99 headers with MSVC versions that have (some) C99 support

include/msvc_compat/C99/stdbool.h

@@ -0,0 +1,16 @@
+#ifndef stdbool_h
+#define stdbool_h
+
+#include <wtypes.h>
+
+/* MSVC doesn't define _Bool or bool in C, but does have BOOL */
+/* Note this doesn't pass autoconf's test because (bool) 0.5 != true */
+typedef BOOL _Bool;
+
+#define bool _Bool
+#define true 1
+#define false 0
+
+#define __bool_true_false_are_defined 1
+
+#endif /* stdbool_h */