[OPENMP] Add support for OMP5 requires directive + unified_address clause

Add support for OMP5.0 requires directive and unified_address clause.
Patches to follow will include support for additional clauses.

Differential Revision: https://reviews.llvm.org/D52359

llvm-svn: 343063
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index 44ee6b3..e74066e 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -105,6 +105,7 @@
   case Decl::Import:
   case Decl::OMPThreadPrivate:
   case Decl::OMPCapturedExpr:
+  case Decl::OMPRequires:
   case Decl::Empty:
     // None of these decls require codegen support.
     return;
@@ -2146,3 +2147,7 @@
     return;
   getOpenMPRuntime().emitUserDefinedReduction(CGF, D);
 }
+
+void CodeGenModule::EmitOMPRequiresDecl(const OMPRequiresDecl *D) {
+  //Do nothing - here to avoid build errors
+}