Use a range based for loop for the SubtargetFeatures print function.

llvm-svn: 208132
diff --git a/llvm/lib/MC/SubtargetFeature.cpp b/llvm/lib/MC/SubtargetFeature.cpp
index 844df0a..3be6d96 100644
--- a/llvm/lib/MC/SubtargetFeature.cpp
+++ b/llvm/lib/MC/SubtargetFeature.cpp
@@ -309,8 +309,8 @@
 /// print - Print feature string.
 ///
 void SubtargetFeatures::print(raw_ostream &OS) const {
-  for (size_t i = 0, e = Features.size(); i != e; ++i)
-    OS << Features[i] << "  ";
+  for (auto &F : Features)
+    OS << F << " ";
   OS << "\n";
 }