Win32: Use constants in version resource definitions where possible

Signed-off-by: Sven Strickroth <email@cs-ware.de>

src/win32/git2.rc

@@ -12,13 +12,13 @@ VS_VERSION_INFO		VERSIONINFO	MOVEABLE IMPURE LOADONCALL DISCARDABLE
   PRODUCTVERSION	LIBGIT2_VER_MAJOR,LIBGIT2_VER_MINOR,LIBGIT2_VER_REVISION,0
   FILEFLAGSMASK		VS_FFI_FILEFLAGSMASK
 #ifdef _DEBUG
-  FILEFLAGS		1
+  FILEFLAGS		VS_FF_DEBUG
 #else
   FILEFLAGS		0
 #endif
   FILEOS		VOS_NT_WINDOWS32
   FILETYPE		VFT_DLL
-  FILESUBTYPE		0	// not used
+  FILESUBTYPE	VFT2_UNKNOWN
 BEGIN
   BLOCK "StringFileInfo"
   BEGIN