Remove unnecessary classof()'s

isa<> et al. automatically infer when the cast is an upcast (including a
self-cast), so these are no longer necessary.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165767 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/User.h

@@ -176,7 +176,6 @@ public:
   void replaceUsesOfWith(Value *From, Value *To);
 
   // Methods for support type inquiry through isa, cast, and dyn_cast:
-  static inline bool classof(const User *) { return true; }
   static inline bool classof(const Value *V) {
     return isa<Instruction>(V) || isa<Constant>(V);
   }