8253239: Disable VS warning C4307

Reviewed-by: mdoerr, erikj

Author: MBaesken

make/autoconf/flags-cflags.m4

@@ -134,6 +134,10 @@ AC_DEFUN([FLAGS_SETUP_WARNINGS],
 
       WARNINGS_ENABLE_ALL="-W3"
       DISABLED_WARNINGS="4800"
+      if test "x$TOOLCHAIN_VERSION" = x2017; then
+        # VS2017 incorrectly triggers this warning for constexpr
+        DISABLED_WARNINGS+=" 4307"
+      fi
       ;;
 
     gcc)