GDB related changes

[J. Johnston]

I have checked in some changes to the configrun-sid.in file, the pregenerated conf files,
and the gdb component to support hardware reset when programs are being rerun or
restarted under gdb using sid.

In the gdb component, a new output pin "restart" is added which is driven when
sid recognizes a gdb program restart ("run" under "target extended-remote").  This is
tied to the hw-reset-net so registers/etc are reset properly before restarting the program.

In addition, --gdb=xxxx now infers --persistent and also sets the gdb "exit-on-detach?"
setting to true.  This handles the "target remote" case and also when gdb is terminated
and rerun such that it reattaches to the server.

The change has been approved by Frank.

-- Jeff J.