[RFA] Fix crash when command arg is missing in faas/taas/tfaas commands.

[Philippe Waroquiers]

On Thu, 2019-12-05 at 23:08 +0000, Andrew Burgess wrote:
> * Philippe Waroquiers <philippe.waroquiers@skynet.be> [2019-12-06 00:05:25 +0100]:
> 
> > GDB crashes when doing:
> >   (gdb) faas
> >   Aborted
> > 
> > Do the needed check to avoid crashing.
> > 
> > gdb/ChangeLog
> > 2019-12-05  Philippe Waroquiers  <philippe.waroquiers@skynet.be>
> > 	* stack.c (faas_command): Check a command is provided.
> > 	* thread.c (taas_command, tfaas_command): Likewise.
> > 
> > gdb/testsuite/ChangeLog
> > 2019-12-05  Philippe Waroquiers  <philippe.waroquiers@skynet.be>
> > 
> > 	* gdb.threads/pthreads.exp: Test taas and tfaas without command.
> > 	* gdb.base/frameapply.exp: Test faas without command.
> 
> LGTM.
Thanks for the review, pushed.

Philippe