ArrayRef has a OneElt constructor. Beautify the code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176604 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/IR/Constants.cpp b/lib/IR/Constants.cpp
index dafca98..e67e78e 100644
--- a/lib/IR/Constants.cpp
+++ b/lib/IR/Constants.cpp
@@ -1417,8 +1417,7 @@
   LLVMContextImpl *pImpl = Ty->getContext().pImpl;
 
   // Look up the constant in the table first to ensure uniqueness.
-  ArrayRef<Constant*> Ops(&C, 1);
-  ExprMapKeyType Key(opc, Ops);
+  ExprMapKeyType Key(opc, C);
 
   return pImpl->ExprConstants.getOrCreate(Ty, Key);
 }