some testing and gdbstub fixes This is mostly gdbstub focused but I cleaned up some bits while I was in the testing makefiles. This is mostly to make the "check-tcg" output as clean as possible without ugly line wraps. I tried to eliminate the gdbstub info() output but sadly this is harder than expected. I've tweaked the gdbstub handling for Ctrl-c packets as suggested by Matheus. While I was there I also noticed we were being a bit precious about gdb sending preemptive ACKS so I fixed that as well. I don't know if this is all late 8.1-rc material but its fairly simple testing updates and the ccache stuff from Daniel should help as well.