[OPENMP50]Add parsing/sema analysis for nontemporal clause.

Add basic support for parsing/sema analysis of the nontemporal clause in
simd-based directives.
diff --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index 9dbbcc0..181ed33 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -2194,6 +2194,7 @@
   case OMPC_use_device_ptr:
   case OMPC_is_device_ptr:
   case OMPC_allocate:
+  case OMPC_nontemporal:
     Clause = ParseOpenMPVarListClause(DKind, CKind, WrongDirective);
     break;
   case OMPC_device_type: