Replace string GNU Triples with llvm::Triple in MCSubtargetInfo and create*MCSubtargetInfo(). NFC.

Summary:
This continues the patch series to eliminate StringRef forms of GNU triples
from the internals of LLVM that began in r239036.

Reviewers: rafael

Reviewed By: rafael

Subscribers: rafael, ted, jfb, llvm-commits, rengolin, jholewinski

Differential Revision: http://reviews.llvm.org/D10311

llvm-svn: 239467
diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
index ac68a06..353c20b 100644
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -564,7 +564,7 @@
   // anyhow.
   // FIXME: For ifunc related functions we could iterate over and look
   // for a feature string that doesn't match the default one.
-  StringRef TT = TM.getTargetTriple();
+  const Triple TT(TM.getTargetTriple());
   StringRef CPU = TM.getTargetCPU();
   StringRef FS = TM.getTargetFeatureString();
   std::string ArchFS = ARM_MC::ParseARMTriple(TT, CPU);