Eliminate Sema::CompareMethodParamsInBaseAndSuper() entirely, by

folding its one check into the normal path for checking overridden
Objective-C methods. Good for another 3.6% speedup on the test case in
<rdar://problem/11004361>.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@155961 91177308-0d34-0410-b5e6-96231b3b80d8