[CIR][CodeGen] Added clang:: namespace qualifier to be consistent with the file

Author: tommymcm

clang/lib/CIR/CodeGen/CIRGenModule.h

@@ -574,7 +574,7 @@ class CIRGenModule : public CIRGenTypeCache {
   std::vector<const clang::CXXRecordDecl *> DeferredVTables;
 
   /// A queue of (optional) vtables that may be emitted opportunistically.
-  std::vector<const CXXRecordDecl *> opportunisticVTables;
+  std::vector<const clang::CXXRecordDecl *> opportunisticVTables;
 
   mlir::Type getVTableComponentType();
   CIRGenVTables &getVTables() { return VTables; }