Use 'rc-update' in 'rc-autoupdate'
Use 'rc-update' in 'rc-autoupdate'

Since a lot of the logic is duplicated, we might as well use the
'rc-update' script to handle actually running the updates, once we check
that they need to be done.

Also, I tweaked the style of the inline variables so that they're more
consistent.

sycobuny/rcfiles,sycobuny/rcfiles