Add explicit keywords.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53179 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index 1dea2ee..09563c4 100644
--- a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -45,7 +45,7 @@
     const PPCSubtarget &PPCSubTarget;
     unsigned GlobalBaseReg;
   public:
-    PPCDAGToDAGISel(PPCTargetMachine &tm)
+    explicit PPCDAGToDAGISel(PPCTargetMachine &tm)
       : SelectionDAGISel(PPCLowering), TM(tm),
         PPCLowering(*TM.getTargetLowering()),
         PPCSubTarget(*TM.getSubtargetImpl()) {}