(checksect, give_back_cap, guerrilla): No longer change capital to

(checksect, give_back_cap, guerrilla): No longer change capital to
agribusiness.  That was done when the occupier abandons the old-owners
capital or it revolts, to prevent players from sacking the same
capital many timers.  The server has a much better way to prevent that
since 4.2.7, so this weird hack is no longer useful.  Thanks to Pat
Loney for pointing this out.