Ninja: remove GCC -Wshadow warning

Source/cmNinjaNormalTargetGenerator.cxx

@@ -432,7 +432,7 @@ void cmNinjaNormalTargetGenerator::WriteLinkStatement()
   // If we have any PRE_LINK commands, we need to go back to HOME_OUTPUT for
   // the link commands.
   if (!preLinkCmdLines.empty()) {
-    std::string path = this->GetLocalGenerator()->ConvertToOutputFormat(
+    path = this->GetLocalGenerator()->ConvertToOutputFormat(
       this->GetMakefile()->GetHomeOutputDirectory(),
       cmLocalGenerator::SHELL);
     preLinkCmdLines.push_back("cd " + path);