[RFA+doco/NEWS-RFA] Add support for --start option in -exec-run GDB/MI command.

[Tom Tromey]

>>>>> "Joel" == Joel Brobecker <brobecker@adacore.com> writes:

Joel> Attached is an updated patch, which includes cleaned-up implementation,
Joel> doco + NEWS, and testing.

The code bits look good to me.

Tom