Objective-C. Change to method lookup rules to look
into primary class's named categories before looking 
into their protocols. This is because categories are
part of the public interface and , just as primary class,
preference should be given to them before class 
(and category) protocols.  // rdar://18013929


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@216610 91177308-0d34-0410-b5e6-96231b3b80d8