Pass StringRef by value.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86251 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCSectionMachO.cpp b/lib/MC/MCSectionMachO.cpp
index b3aeb9c..6cc67a2 100644
--- a/lib/MC/MCSectionMachO.cpp
+++ b/lib/MC/MCSectionMachO.cpp
@@ -66,7 +66,7 @@
 
 
 MCSectionMachO *MCSectionMachO::
-Create(const StringRef &Segment, const StringRef &Section,
+Create(StringRef Segment, StringRef Section,
        unsigned TypeAndAttributes, unsigned Reserved2,
        SectionKind K, MCContext &Ctx) {
   // S_SYMBOL_STUBS must be set for Reserved2 to be non-zero.