#966 A gdbserver protocol interface for uCsim

[Philipp Klaus Krause]

The uCsim simulator has its own command line user interface, and can be used with the SDCDB debugger (which supports the CDB debug info format that all SDCC ports can emit); but GDB is substantially more powerful in many ways, and many IDEs can interact with it, so it would be great, if GDB could be used with the uCsim simulators.