Patch for PR23175, Infinite loop iterating Objective-C method declarations

Could someone be so kind as to review the patches attached to PR23175 and, assuming no concerns, commit them?

Bug 23175 - Infinite loop iterating Objective-C method declarations in categories when the AST was deserialized from an .ast file
https://llvm.org/bugs/show_bug.cgi?id=23175

Thank you,
Tom.

Please send patches to cfe-commits or use Phabricator, they’ll just get lost in the issue tracker. Make sure you CC someone as well.