Summary:
This ignores case while sorting using-declarations, fixing a case where `_` would appear between lowercase and uppercase characters.
It also applies stable sort, so that replacements for the exact same using declarations are not generated.
Reviewers: klimek, alexfh
Reviewed By: alexfh
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D37263
llvm-svn: 313963