Summary:
This is part 1 of 3 of a series of changes to improve Objective-C
linting in clang-tidy.
This introduces a new clang-tidy module, `objc`, specifically for
Objective-C / Objective-C++ checks.
The module is currently empty; D39142 adds the first check.
Test Plan: `ninja check-clang-tools`
Patch by Ben Hamilton!
Reviewers: hokein, alexfh
Reviewed By: hokein
Subscribers: Wizard, mgorny
Differential Revision: https://reviews.llvm.org/D39188
llvm-svn: 316643