[NFC] Warning cleanup (#11831)

Unused variable - clean it up.

Author: mdtoguchi

clang/lib/Driver/ToolChains/Clang.cpp

@@ -6114,10 +6114,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     A->render(Args, CmdArgs);
   }
 
-  if (Arg *A = Args.getLastArg(options::OPT_faltmathlib_EQ)) {
-    StringRef Name = A->getValue();
+  if (Arg *A = Args.getLastArg(options::OPT_faltmathlib_EQ))
     A->render(Args, CmdArgs);
-  }
 
   if (Args.hasFlag(options::OPT_fmerge_all_constants,
                    options::OPT_fno_merge_all_constants, false))