Add explicit keywords.

llvm-svn: 72969
diff --git a/llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.h b/llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.h
index 42883d7..b359dd3 100644
--- a/llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.h
+++ b/llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.h
@@ -59,7 +59,7 @@
   bool HasFastCall;
 
 public:
-  PPCFunctionInfo(MachineFunction &MF) 
+  explicit PPCFunctionInfo(MachineFunction &MF) 
     : FramePointerSaveIndex(0),
       ReturnAddrSaveIndex(0),
       SpillsCR(false),