Honor attribute 'analyzer_noreturn' on Objective-C methods.

This isn't likely a full solution, but it catches the common cases
and can be refined over time.

Fixes <rdar://problem/11634353>.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@173291 91177308-0d34-0410-b5e6-96231b3b80d8
Add missing null check.  Not sure why my tests passed before.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@173292 91177308-0d34-0410-b5e6-96231b3b80d8
Always process an index.html file if we have HTML output.  Patch by Justin Bogner.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@173294 91177308-0d34-0410-b5e6-96231b3b80d8
Add a test case for 'analyzer_noreturn' on category methods.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@173295 91177308-0d34-0410-b5e6-96231b3b80d8