To better support building RPMs for multiple distribution versions, we
need a bit of help to organize the RPMs. We take the path of adding a
'rpms/7.4.1708' style directory, with the implicit knowledge this is for
CentOS and RHEL. Other distribution handling is left for the future.
To ease DOCKER_IMAGE selection for different distribution versions, the
environment variable DISTRO_VERS can be used. This simplifies a bunch of
call locations and scripting when we don't need to change the Docker
image flavor beyond this distribution version toggle.
i.e: DISTRO_VERS=el73 ./indocker.sh ./build_rpms.sh
The directory tree ends up looking like this:
rpms/7.4.1708/kmod-scoutfs-1.0-0.git.5fee207.el7.x86_64.rpm
rpms/7.3.1611/kmod-scoutfs-1.0-0.git.5fee207.el7.x86_64.rpm