BUG: Unignore .c files under _libs/src. (#42116)
- [x] closes #42116

Not 100% what tests I could write for this. This works locally. git status shows no untracked files while `rg on_bad_lines` now shows results from `pandas/_libs/src/parser/tokenizer.c`
this is to not include the source in the distribution? where is this breaking? This pull request is stale because it has been open for thirty days with no activity. Please update or respond to this comment if you're still interested in working on this. @dalejung can you address https://github.com/pandas-dev/pandas/pull/42117#issuecomment-873667846 and merge upstream/master (should fix ci) Thanks for the PR, but it appears to have gone stale. Let us know if you're still interested in working on this and we can reopen. Closing.