[OpenMP] Parsing and sema support for the from clause

Summary:
The patch contains the parsing and sema support for the `from` clause. 

Patch based on the original post by Kelvin Li.

Reviewers: hfinkel, carlo.bertolli, kkwli0, arpith-jacob, ABataev

Subscribers: caomhin, cfe-commits

Differential Revision: http://reviews.llvm.org/D18488

llvm-svn: 270882
diff --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index 22b0b31..688530b 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -494,6 +494,9 @@
 void OMPClauseProfiler::VisitOMPToClause(const OMPToClause *C) {
   VisitOMPClauseList(C);
 }
+void OMPClauseProfiler::VisitOMPFromClause(const OMPFromClause *C) {
+  VisitOMPClauseList(C);
+}
 }
 
 void