Add missing function definition (TranslateClauseWithTerminator)

[danemadsen]

This function was added to the translate.h header in #1811 but the associated function definition was not added to translate.c

[iSuslov]

Hey @danemadsen, do you think we need to add additional modifications with ESPEAK_API as it's implemented here: ba13f63

[sthibaul]

There was an unrelated drop of memset(number_buf, 0, sizeof(number_buf));, which was caught by CI, but ignored for some time. That's confirmed with

https://github.com/espeak-ng/espeak-ng/actions/runs/9749747800 (CI re-run before commit, works)
https://github.com/espeak-ng/espeak-ng/actions/runs/9749753923 (CI re-run with the commit, fails)
https://github.com/espeak-ng/espeak-ng/actions/runs/9749896365 (CI run with memset restored, works)

Please do not ignore CI failures, they are protections against security issues.

This is getting fixed by #1942