Make installer compression tool configurable
So we can use pigz or other parallelizable tools if available. Shaves
off noticeable build time when packaging install sets.
- figure out if pigz is available (fallback to gzip otherwise)
- pass compression tool down into make_installer
- and handle as one of many global options there
Change-Id: Ia9d1ea27a9f990874238b6f0be3e1fd30a662ec6
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/128469
Tested-by: Jenkins
Reviewed-by: Thorsten Behrens <thorsten.behrens@allotropia.de>