build-auto.sh: Allow non-ceph builds to be run

Look for matching build scripts based on the hostname for non-ceph
builds (such as samba).

Signed-off-by: Sam Lang <sam.lang@inktank.com>
samba: Update samba build script

Updates to the samba build script to more closely match the other
autobuilder scripts for ceph.

Signed-off-by: Sam Lang <sam.lang@inktank.com>
samba: Change hostname for samba gitbuilder

Signed-off-by: Sam Lang <sam.lang@inktank.com>