build_all_repos: Use more bash-isms, address issues flagged by shellcheck
build_all_repos: Use more bash-isms, address issues flagged by shellcheck

* Use $* instead of $@ when concatenating with a string.
* Declare and export environment variables separately.
* Double quote array expansions, otherwise they're like $* and break on spaces.
* Double quote lots of variables to prevent globbing and word splitting.
* Remove unnecessary from $/${} arithmetic variables.
* Use globs rather than iterating over ls output.
* Quote parameters to tr to prevent glob expansion.
* Use ${variable//search/replace} instead of piping to sed where possible.
* Use $(..) instead of legacy `..`.
* Use [[ ]] rather than [ ] to reduce number of sub-processes.

jrha/release,jrha/release,wdpypere/release,jrha/release,wdpypere/release,quattor/release,wdpypere/release,quattor/release,quattor/release