[OpenMP] Parsing + sema for defaultmap clause.

Summary:
This patch adds parsing + sema for the defaultmap clause associated with the target directive (among others).

Reviewers: ABataev

Differential Revision: http://reviews.llvm.org/D16527

llvm-svn: 258817
diff --git a/clang/lib/CodeGen/CGStmtOpenMP.cpp b/clang/lib/CodeGen/CGStmtOpenMP.cpp
index a6abbba..2ea9b0f 100644
--- a/clang/lib/CodeGen/CGStmtOpenMP.cpp
+++ b/clang/lib/CodeGen/CGStmtOpenMP.cpp
@@ -2564,6 +2564,7 @@
   case OMPC_num_tasks:
   case OMPC_hint:
   case OMPC_dist_schedule:
+  case OMPC_defaultmap:
     llvm_unreachable("Clause is not allowed in 'omp atomic'.");
   }
 }