Return true on success in cl::ExpandResponseFiles

This fixes a logic bug pointed out by Juraj Ivancic.

No behavior change because none of the in-tree clients of
cl::ExpandResponseFiles check the return value.  In this case, the
@prefixed arguments are left in the command line.  Downstream command
line processing has the opportunity to emit errors about it, so this
isn't that bad.

llvm-svn: 196306

llvm/lib/Support/CommandLine.cpp

@@ -634,7 +634,7 @@ static bool ExpandResponseFile(const char *FName, StringSaver &Saver,
 bool cl::ExpandResponseFiles(StringSaver &Saver, TokenizerCallback Tokenizer,
                              SmallVectorImpl<const char *> &Argv) {
   unsigned RspFiles = 0;
-  bool AllExpanded = false;
+  bool AllExpanded = true;
 
   // Don't cache Argv.size() because it can change.
   for (unsigned I = 0; I != Argv.size(); ) {