add fast-math flag in clang-cl

Author: pgorlani

clang/include/clang/Driver/Options.td

@@ -1542,7 +1542,7 @@ def ffp_exception_behavior_EQ : Joined<["-"], "ffp-exception-behavior=">, Group<
   MarshallingInfoEnum<LangOpts<"FPExceptionMode">, "FPE_Ignore">;
 defm fast_math : BoolFOption<"fast-math",
   LangOpts<"FastMath">, DefaultFalse,
-  PosFlag<SetTrue, [CC1Option], "Allow aggressive, lossy floating-point optimizations",
+  PosFlag<SetTrue, [CC1Option, CoreOption], "Allow aggressive, lossy floating-point optimizations",
           [cl_fast_relaxed_math.KeyPath]>,
   NegFlag<SetFalse>>;
 def menable_unsafe_fp_math : Flag<["-"], "menable-unsafe-fp-math">, Flags<[CC1Option]>,