Include bus errors and aborts, as well as segmentation violations, as

Include bus errors and aborts, as well as segmentation violations, as
examples of errors that generate core dumps, and suggest that a stack
trace from the debugger could be useful for *all* failures that produce
core dumps.

Note that the core dump file may be named "ethereal.core", and note that
"tethereal" rather than "ethereal" should be used in file names if it's
Tethereal that blew up.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@2368 f5534014-38df-0310-8fa8-9805f1628bb7