Yep, Mac OS X it's gone but on Linux it's there for me (last time I checked). The about:config entry will work fine either case.
It's nothing to do with your profile because this is the same profile on both machines for me.
IIRC I brought this up a long time ago, and just ignored the issue because the about:config entry for that GUI item works fine...
(Note that that option has no meaning in Firefox or other Gecko-based applications with no actual status bar, so it makes sense that it's hidden in some cases.)
*Always* check the changelogs BEFORE updating that important software!