Run clang-tidy's performance-unnecessary-copy-initialization over LLVM.

No functionality change intended.

llvm-svn: 272516
diff --git a/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp b/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
index 3954ee7..4d71d20 100644
--- a/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
@@ -1830,7 +1830,7 @@
       unsigned LISInstr = is64Bit ? PPC::LIS8 : PPC::LIS;
       unsigned ORIInstr = is64Bit ? PPC::ORI8 : PPC::ORI;
       MachineInstr *MI = I;
-      DebugLoc dl = MI->getDebugLoc();
+      const DebugLoc &dl = MI->getDebugLoc();
 
       if (isInt<16>(CalleeAmt)) {
         BuildMI(MBB, I, dl, TII.get(ADDIInstr), StackReg)