[OpenMP] Parsing + sema for target parallel directive.

Summary:
This patch adds parsing + sema for the target parallel directive and its clauses along with testcases.

Reviewers: ABataev

Differential Revision: http://reviews.llvm.org/D16553

Rebased to current trunk and updated test cases.

llvm-svn: 258832
diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index c884b14..25b8dd8 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -2282,7 +2282,11 @@
    */
   CXCursor_OMPTargetExitDataDirective    = 262,
 
-  CXCursor_LastStmt                      = CXCursor_OMPTargetExitDataDirective,
+  /** \brief OpenMP target parallel directive.
+   */
+  CXCursor_OMPTargetParallelDirective    = 263,
+
+  CXCursor_LastStmt                      = CXCursor_OMPTargetParallelDirective,
 
   /**
    * \brief Cursor that represents the translation unit itself.