Add [FLAG]... arguments to 'thread apply'.

Add [FLAG]... arguments to 'thread apply'.

Enhance 'thread apply' command to also accept [FLAG]... arguments.

An example usage for this new argument:
   thread apply all -s frame apply all -s p some_local_var_somewhere
      Prints the thread id, frame location and some_local_var_somewhere
      value in frames of threads that have such local var.

To make the life of the user easier, the most typical use cases
have shortcuts :
   taas  : shortcut for 'thread apply all -s'
   tfaas : shortcut for 'thread apply all -s frame apply all -s"

An example usage :
   tfaas p some_local_var_somewhere
     same as the longer:
        'thread apply all -s frame apply all -s p some_local_var_somewhere'

gdb/ChangeLog
2018-07-12  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* thread.c (thr_try_catch_cmd): New function.
	(thread_apply_all_command): Handle qcs flags.
	(thread_apply_command): Handle qcs flags.
	(taas_command): New function.
	(tfaas_command): New function.
	(_initialize_thread): Update to setup the new commands 'taas
	and 'tfaas'. Change doc string for 'thread apply'.