MFC r322552 by jhb: Unconditionally install rwhod support scripts.

r322277 moved rwho* and ruptime out of the MK_RCMDS conditional including
updating the obsolete files entries to not remove these scripts due to
WITHOUT_RCMDS=yes. However, the initial installation was still conditional
on MK_RCMDS, so new installs did not include these scripts and upgrades via
mergemaster or etcupdate removed them.

PR: 220953