Several improvements
- Only add files that we actually want to format.
- Sort according to a fixed locale.
Some drive-by fixes
- Rename a text file, this avoids a filter exception.
- Adds a some missing source files extensions.
- Removes unused extensions hh, hxx, cc, and cxx from clang-format.
Reviewed By: philnik, #libc
Differential Revision: https://reviews.llvm.org/D144126
It is quite confusing to newcomers that the formatting check gets mostly ignored. To fix that, enforce the formatting for new file and already formatted files, but ignore it for any files that aren't formatted already. We ignore the tests for now, since almost no test is formatted currently, and they are changed almost never.
Reviewed By: ldionne, Mordante, #libc
Spies: arichardson, fedor.sergeev, phosek, sstefan1, libcxx-commits, abrachet
Differential Revision: https://reviews.llvm.org/D142180
