Fixed a bug where pdbname is not set with external validator (#2314)

tools/clang/tools/dxcompiler/dxcutil.cpp

@@ -183,12 +183,13 @@ HRESULT ValidateAndAssembleToContainer(
     // module.
     if (bDebugInfo) {
       llvmModule.CloneForDebugInfo();
-      if (DebugName.size()) {
-        llvmModule.SetDebugName(DebugName);
-      }
     }
   }
 
+  if (bDebugInfo && DebugName.size()) {
+    llvmModule.SetDebugName(DebugName);
+  }
+
   llvmModule.WrapModuleInDxilContainer(pMalloc, pOutputStream, pOutputBlob,
                                        SerializeFlags, pShaderHashOut);