[BusyBox] start of ash optimizations

[Aaron Lehmann]

This is really minor for its size, and removes only about 132 bytes
from the i386 excecutable. All it really does is removes some
functions that were only called from one place.

Next on my chopping block is the signal_names array -- do we really
need all those signals?? Couldn't we use strsignal(3) or something
similar? I'm in favor of at least leaving out the SIGRT* mess.

Sorry for making the diff so stupid, but I gotta go pack :-).