RFC strace via gdbserver

[Stan Cox]

> Can you explain your -f changes?
>
> I see you're alternating QCatchSyscalls:1 or QCatchSyscalls:2 -- what
> are these values?  Has this protocol change gone into gdb upstream, or
> just your own gdb branch?
Yes, it was just a local change.  QCatchSyscalls:1 was without -f being specified and QCatchSyscalls:2 was when -f was specified.  On the gdbserver side it is translated to:
  <-2,SYSCALL1,...,SYSCALLN> follow syscalls in list
  OR <-2,-1)  follow all syscalls
  OR (-1) all syscalls

> have thought we just needed to add fork-events+ and vfork-events+ to our
> qSupported string.
Hmm yea, so add fork-events+ and vfork-events+ and just make following clones the default?
a list of syscalls  would be $QCatchSyscalls:1;0;1;2;3;4;5;6;7;8;9;
all syscalls would be $QCatchSyscalls:1

  That seems reasonable to me.
> PS- on git procedure ... I'd suggest you either rebase or
> reset and cherry-pick new changes, so we can keep it easier to see what
> the gdbserver changes are.
Sure thing