[pragma] Silence MSVC unknown-pragma warning
diff --git a/src/hb.hh b/src/hb.hh
index 860236b..5b66ba8 100644
--- a/src/hb.hh
+++ b/src/hb.hh
@@ -30,6 +30,9 @@
 #define HB_HH
 
 #ifndef HB_NO_PRAGMA_GCC_DIAGNOSTIC
+#if defined(_MSC_VER)
+#pragma warning( disable: 4068 ) /* Unknown pragma */
+#endif
 #if defined(__GNUC__) || defined(__clang__)
 /* Rules:
  *