GDBserver response when breakpoint reached

[ccrause]

I'm testing dwire-debug with the Lazarus IDE using gdb for debugging. When hitting a breakpoint the IDE would pop up an error notification that a External: 0 was received. According to https://sourceware.org/gdb/onlinedocs/gdb/Stop-Reply-Packets.html#Stop-Reply-Packets gdb expects a SIGTRAP (= 5) response when the target reached a breakpoint.

I've modified the responses for '?', 'c', 's' commands to "S05" in handle_command (rsp.c) and the Lazarus IDE now behaves as expected during debugging. Since this is the expected response I suggest the source gets updated accordingly.

Great work by the way.