RFC: implement "catch signal"

[Tom Tromey]

>>>>> "Jan" == Jan Kratochvil <jan.kratochvil@redhat.com> writes:

Jan> body=[bkpt={number="1",type="catchpoint",disp="keep",enabled="y",what="<signal>",signal=["SIGINT","SIGTRAP"],times="0"}]

I see now that the "type" field for catchpoints is not very useful.

I think we should make that change depending on the particular type of
catchpoint that is installed.  Thoughts on this?

Tom