Fix fp-model flag test failure on linux

We're still in the awkward state where IEEE is not the default
denormal mode.

clang/lib/Driver/ToolChains/Clang.cpp

@@ -2771,7 +2771,8 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
       if (HonorINFs && HonorNaNs &&
         !AssociativeMath && !ReciprocalMath &&
         SignedZeros && TrappingMath && RoundingFPMath &&
-        DenormalFPMath != llvm::DenormalMode::getIEEE() &&
+        // FIXME: This should check for IEEE when it's the default.
+        DenormalFPMath != llvm::DenormalMode::getInvalid() &&
         FPContract.equals("off"))
         // OK: Current Arg doesn't conflict with -ffp-model=strict
         ;