Driver: Change Arg::render methods to use option name instead of string where
possible.

llvm-svn: 105738
diff --git a/clang/lib/Driver/Arg.cpp b/clang/lib/Driver/Arg.cpp
index 7e61a1d..8243cab 100644
--- a/clang/lib/Driver/Arg.cpp
+++ b/clang/lib/Driver/Arg.cpp
@@ -79,7 +79,7 @@
 }
 
 void FlagArg::render(const ArgList &Args, ArgStringList &Output) const {
-  Output.push_back(Args.getArgString(getIndex()));
+  Output.push_back(getOption().getName());
 }
 
 const char *FlagArg::getValue(const ArgList &Args, unsigned N) const {
@@ -159,7 +159,7 @@
     Output.push_back(Args.MakeArgString(llvm::StringRef(getOption().getName()) +
                                         getValue(Args, 0)));
   } else {
-    Output.push_back(Args.getArgString(getIndex()));
+    Output.push_back(getOption().getName());
     for (unsigned i = 0; i < NumValues; ++i)
       Output.push_back(getValue(Args, i));
   }