... it is an abbreviation of "Solar Version".

Since nobody can remember that:

remove OUTDIR OUTDIR_FOR_BUILD SOLARVER SOLARVERSION solarpath
and any mention thereof.

Change-Id: Idb3031c4f25a76ac05b22ec67e3ca3e1e8e512ad
Reviewed-on: https://gerrit.libreoffice.org/6515Tested-by: LibreOffice gerrit bot <gerrit@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>