-Warc-repeated-use-of-weak: check ivars and variables as well.

-Warc-repeated-use-of-weak: check ivars and variables as well.

Like properties, loading from a weak ivar twice in the same function can
give you inconsistent results if the object is deallocated between the
two loads. It is safer to assign to a strong local variable and use that.

Second half of <rdar://problem/12280249>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@164855 91177308-0d34-0410-b5e6-96231b3b80d8