Fix strptime era handling, add more era tests [BZ #24394]

[DJ Delorie]

Rafal Luzynski <digitalfreak@lingonborough.com> writes:
> I think we have already written UTF-8 codes explicitly in some other
> tests so I think it would be OK here as well.  However, I'd like to
> see the actual glyphs written in the comment to explain what these
> binary codes should mean.  I think it is nice for a potential reviewer
> who is able to read this particular script.

I don't mind having UTF-8 in comments, but... it always works in gcc,
right?

And that leads to the question "what about tests for non-utf8 locales" ?
Do we put the UTF-8 glyphs in the comments, or just omit them?