clang-cl: Parse /openmp:experimental

It was added to the MS docs recently here:
MicrosoftDocs/cpp-docs@3951085

llvm-svn: 358570

Author: zmodem

clang/include/clang/Driver/CLCompatOptions.td

@@ -428,6 +428,7 @@ def _SLASH_kernel : CLFlag<"kernel">;
 def _SLASH_LN : CLFlag<"LN">;
 def _SLASH_MP : CLJoined<"MP">;
 def _SLASH_openmp : CLFlag<"openmp">;
+def _SLASH_openmp_experimental : CLFlag<"openmp:experimental">;
 def _SLASH_Qfast_transcendentals : CLFlag<"Qfast_transcendentals">;
 def _SLASH_QIfist : CLFlag<"QIfist">;
 def _SLASH_Qimprecise_fwaits : CLFlag<"Qimprecise_fwaits">;

clang/test/Driver/cl-options.c

@@ -442,6 +442,7 @@
 // RUN:     /o foo.obj \
 // RUN:     /ofoo.obj \
 // RUN:     /openmp \
+// RUN:     /openmp:experimental \
 // RUN:     /Qfast_transcendentals \
 // RUN:     /QIfist \
 // RUN:     /Qimprecise_fwaits \