date: fix strftime O/E modifier parsing in C locale

[Jah-yee]

Good day,

Thank you for your work on this project. I hope this small fix is helpful.
Please let me know if there's anything to adjust.

Warmly, RoomWithOutRoof

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/date/date-locale-hour (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/pr/bounded-memory (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/tail/retry is no longer failing!
Note: The gnu test tests/tail/tail-n0f is now being skipped but was previously passing.
Congrats! The gnu test tests/cut/cut-huge-range is now passing!

[Alonely0]

@Jah-yee Thank you for your contribution, and welcome to the repo! I'm really sorry to say that I'm going to approve #11834 instead of this one, because the fixes are more complete (notice that if you cherry-pick both test-adding commits on that PR onto your branch, the E modifier still has some issues). I'm going to have to lightly scold the other author for that git etiquette tho, hahahah.

[Jah-yee]

@Jah-yee Thank you for your contribution, and welcome to the repo! I'm really sorry to say that I'm going to approve #11834 instead of this one, because the fixes are more complete (notice that if you cherry-pick both test-adding commits on that PR onto your branch, the E modifier still has some issues). I'm going to have to lightly scold the other author for that git etiquette tho, hahahah.

No problem at all～Thx for your kind words and for your review！

I will go ahead and close this.