truss firefox hangs or crashes

[Johannes Hofmann <johannes.hofmann@xxxxxx>]

	truss firefox
hangs or segfaults. Same with e.g. dillo. 
This patch provided by tuxillo on irc:
http://leaf.dragonflybsd.org/~hofmann/truss.diff
fixes the crashes, but there may be more checks needed. I'm also
wondering why there is unknown syscalls at all.

Cheers,
Joahnnes