libtecla: 10.8> fixes.

Closes #33733.
I'm not sure there is anywhere to report it upstream, to be honest. The [website](http://www.astro.caltech.edu/~mcs/tecla/index.html) hasn't been updated in two years, and seems to be fairly abandoned. I guess I can try emailing the link, but even then we wouldn't have anywhere to link to :/.