Replace string GNU Triples with llvm::Triple in TargetMachine::getTargetTriple(). NFC.

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

Reviewers: rengolin

Reviewed By: rengolin

Subscribers: llvm-commits, rengolin

Differential Revision: http://reviews.llvm.org/D10381

llvm-svn: 239815
diff --git a/llvm/lib/Target/TargetMachineC.cpp b/llvm/lib/Target/TargetMachineC.cpp
index 623b3e8..7199235 100644
--- a/llvm/lib/Target/TargetMachineC.cpp
+++ b/llvm/lib/Target/TargetMachineC.cpp
@@ -156,7 +156,7 @@
 }
 
 char* LLVMGetTargetMachineTriple(LLVMTargetMachineRef T) {
-  std::string StringRep = unwrap(T)->getTargetTriple();
+  std::string StringRep = unwrap(T)->getTargetTriple().str();
   return strdup(StringRep.c_str());
 }