[objc-arc] Test cleanups.

Mainly adding paranoid checks for the closing brace of a function to
help with FileCheck error readability. Also some other minor changes.

No actual CHECK changes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180668 91177308-0d34-0410-b5e6-96231b3b80d8