[move-only] Be careful and mark some cleanup as setting changed.

I am pretty sure this would never actually be an issue, but I am trying to just
be careful and consistent.

Author: gottesmm

lib/SILOptimizer/Mandatory/MoveOnlyObjectChecker.cpp

@@ -507,6 +507,7 @@ bool MoveOnlyChecker::check(NonLocalAccessBlockAnalysis *accessBlockAnalysis,
             b.createExplicitCopyValue(cvi->getLoc(), cvi->getOperand());
         cvi->replaceAllUsesWith(expCopy);
         cvi->eraseFromParent();
+        changed = true;
       }
     }
   }