interrupt mask hackery wasn't happening when being modloaded via the
if_ppp lkm. It seems that the lkm system doesn't particularly like having
two sets of load/unload/etc routines. :-] This really should be fixed
by having a seperate if_ppp and ppp_tty lkm, but that requires that ppp_tty
is loaded after if_ppp, and needs to be able to link with symbols in
if_ppp. This gets messy, it is a better task for the in-kernel linker.
(if_ppp is generic, ppp_tty is a tty-specific bottom end for if_ppp, it's
not _too_ hard to have another "provider" (such as a hdlc sync card)
connected to if_ppp)