[clang] [flang] [FLANG] allow -fopenmp= (PR #86816)

[Tom Eccles via cfe-commits]

================
@@ -764,6 +762,32 @@ void Flang::ConstructJob(Compilation &C, const JobAction &JA,
   // Add other compile options
   addOtherOptions(Args, CmdArgs);
 
+  // Forward flags for OpenMP. We don't do this if the current action is an
+  // device offloading action other than OpenMP.
+  if (Args.hasFlag(options::OPT_fopenmp, options::OPT_fopenmp_EQ,
+                   options::OPT_fno_openmp, false) &&
----------------
tblah wrote:

I don't think `-fno-openmp` is visible in the flang driver. Maybe it should be.

https://github.com/llvm/llvm-project/pull/86816