msvc: add pragmas for common warnings

MSVC can be overzealous about some warnings. Disable them.

Signed-off-by: Philip Oakley <[email protected]>
Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Philip Oakley

compat/msvc.h

@@ -6,6 +6,10 @@
 #include <malloc.h>
 #include <io.h>
 
+#pragma warning(disable: 4018) /* signed/unsigned comparison */
+#pragma warning(disable: 4244) /* type conversion, possible loss of data */
+#pragma warning(disable: 4090) /* 'function' : different 'const' qualifiers (ALLOC_GROW etc.)*/
+
 /* porting function */
 #define inline __inline
 #define __inline__ __inline