Return a StringRef from getHostCPUName.

llvm-svn: 197158
diff --git a/llvm/lib/Support/Host.cpp b/llvm/lib/Support/Host.cpp
index b423ada..d883c05 100644
--- a/llvm/lib/Support/Host.cpp
+++ b/llvm/lib/Support/Host.cpp
@@ -193,7 +193,7 @@
   }
 }
 
-std::string sys::getHostCPUName() {
+StringRef sys::getHostCPUName() {
   unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
   if (GetX86CpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX))
     return "generic";