[OPENMP] Fix checks for declare target link entries.

If the declare target link entries are created but not used, the
compiler will produce an error message. Patch improves handling of such
situations + improves checks for possibly lost declare target variables.

llvm-svn: 337207
diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.h b/clang/lib/CodeGen/CGOpenMPRuntime.h
index 599b3ba..01ff0c2 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntime.h
+++ b/clang/lib/CodeGen/CGOpenMPRuntime.h
@@ -522,6 +522,8 @@
     enum OMPTargetGlobalVarEntryKind : uint32_t {
       /// Mark the entry as a to declare target.
       OMPTargetGlobalVarEntryTo = 0x0,
+      /// Mark the entry as a to declare target link.
+      OMPTargetGlobalVarEntryLink = 0x1,
     };
 
     /// Device global variable entries info.