Make FullExprArg trivially copyable by removing the copy ctor

The default copy ctor is good.  This avoids using inalloca for a bunch
of Sema methods when self-hosting.

llvm-svn: 215047

clang/include/clang/Sema/Sema.h

@@ -2946,11 +2946,6 @@ public:
   public:
     FullExprArg(Sema &actions) : E(nullptr) { }
 
-    // FIXME: The const_cast here is ugly. RValue references would make this
-    // much nicer (or we could duplicate a bunch of the move semantics
-    // emulation code from Ownership.h).
-    FullExprArg(const FullExprArg& Other) : E(Other.E) {}
-
     ExprResult release() {
       return E;
     }