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

Summary:
For the moment, TargetMachine::getTargetTriple() still returns a StringRef.

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: ted, llvm-commits, rengolin, jholewinski

Differential Revision: http://reviews.llvm.org/D10362

llvm-svn: 239554
diff --git a/llvm/lib/Target/Hexagon/HexagonTargetMachine.cpp b/llvm/lib/Target/Hexagon/HexagonTargetMachine.cpp
index b1b2b0e..1629118 100644
--- a/llvm/lib/Target/Hexagon/HexagonTargetMachine.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonTargetMachine.cpp
@@ -68,7 +68,7 @@
 
 /// Hexagon_TODO: Do I need an aggregate alignment?
 ///
-HexagonTargetMachine::HexagonTargetMachine(const Target &T, StringRef TT,
+HexagonTargetMachine::HexagonTargetMachine(const Target &T, const Triple &TT,
                                            StringRef CPU, StringRef FS,
                                            const TargetOptions &Options,
                                            Reloc::Model RM, CodeModel::Model CM,
@@ -76,7 +76,7 @@
     : LLVMTargetMachine(T, "e-m:e-p:32:32-i1:32-i64:64-a:0-n32", TT, CPU, FS,
                         Options, RM, CM, OL),
       TLOF(make_unique<HexagonTargetObjectFile>()),
-      Subtarget(Triple(TT), CPU, FS, *this) {
+      Subtarget(TT, CPU, FS, *this) {
     initAsmInfo();
 }