Bug#1039979: base-files: /var/run and /var/lock should not be absolute symlinks

[sohe4b+2fz7rb0ixc53g]

Package: base-files
Version: 12.4
Followup-For: Bug #1039979

PS: making /var/run and /var/lock relative symlinks makes it much nicer and 
safer to work with chroots, avoiding the risk of damaging the real system's /run

It's also what archlinux does.