Add explicit keywords.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53179 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 5cf637e..a3f268f 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -122,8 +122,7 @@
   }
 
 public:
-
-  SelectionDAGLegalize(SelectionDAG &DAG);
+  explicit SelectionDAGLegalize(SelectionDAG &DAG);
 
   /// getTypeAction - Return how we should legalize values of this type, either
   /// it is already legal or we need to expand it into multiple registers of