#328 sdcc reproducible builds issue

[Bernhard M. Wiedemann]

While working on reproducible builds for openSUSE, I found that our sdcc package varies every time, because gputils embeds timestamps in its output in four places.

I attached a PoC patch that helps make it reproducible. Are these timestamps used somewhere? Then we can replace it with the content of the SOURCE_DATE_EPOCH env var as detailled in https://reproducible-builds.org/docs/source-date-epoch/#c