Objective-C. Patch to warn if the result of calling a property getter 
is unused (this is match behavior when property-dot syntax is used to
use same getter). rdar://17514245
Patch by Anders Carlsson with minor refactoring by me.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@213423 91177308-0d34-0410-b5e6-96231b3b80d8