simplify


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@135170 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Basic/Targets.cpp b/lib/Basic/Targets.cpp
index a3cdef1..3518ea6 100644
--- a/lib/Basic/Targets.cpp
+++ b/lib/Basic/Targets.cpp
@@ -3056,7 +3056,7 @@
   for (llvm::StringMap<bool>::const_iterator it = Features.begin(),
          ie = Features.end(); it != ie; ++it)
     Opts.Features.push_back(std::string(it->second ? "+" : "-") +
-                            llvm::StringRef(it->first()).str());
+                            it->first().str());
   Target->HandleTargetFeatures(Opts.Features);
 
   return Target.take();