More explicit keywords.

llvm-svn: 40589
diff --git a/llvm/utils/TableGen/CallingConvEmitter.h b/llvm/utils/TableGen/CallingConvEmitter.h
index a0bfab3..b63fc82 100644
--- a/llvm/utils/TableGen/CallingConvEmitter.h
+++ b/llvm/utils/TableGen/CallingConvEmitter.h
@@ -24,7 +24,7 @@
   class CallingConvEmitter : public TableGenBackend {
     RecordKeeper &Records;
   public:
-    CallingConvEmitter(RecordKeeper &R) : Records(R) {}
+    explicit CallingConvEmitter(RecordKeeper &R) : Records(R) {}
 
     // run - Output the asmwriter, returning true on failure.
     void run(std::ostream &o);