gdbserver/linux-low: turn some static functions into private methods

gdbserver/linux-low: turn some static functions into private methods

gdbserver/ChangeLog:
2020-04-02  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	Turn some static functions in linux-low.cc into private methods of
	linux_process_target.

	* linux-low.cc (handle_extended_wait): Turn into ...
	(linux_process_target::handle_extended_wait): ...this.  Call
	'mourn' on 'this' object instead of 'the_target'.
	(maybe_move_out_of_jump_pad): Turn into...
	(linux_process_target::maybe_move_out_of_jump_pad): ...this.
	(linux_low_filter_event): Turn into...
	(linux_process_target::filter_event): ...this.
	(linux_wait_for_event_filtered): Turn into...
	(linux_process_target::wait_for_event_filtered): ...this.
	(linux_wait_for_event): Turn into...
	(linux_process_target::wait_for_event): ...this.
	(linux_wait_1): Turn into...
	(linux_process_target::wait_1): ...this.
	(wait_for_sigstop): Turn into...
	(linux_process_target::wait_for_sigstop): ...this.
	(move_out_of_jump_pad_callback): Turn into...
	(linux_process_target::move_out_of_jump_pad): ...this.
	(stop_all_lwps): Turn into...
	(linux_process_target::stop_all_lwps): ...this.
	(start_step_over): Turn into...
	(linux_process_target::start_step_over): ...this.
	(complete_ongoing_step_over): Turn into...
	(linux_process_target::complete_ongoing_step_over): ...this.
	(proceed_all_lwps): Turn into...
	(linux_process_target::proceed_all_lwps): ...this.
	(unstop_all_lwps): Turn into...
	(linux_process_target::unstop_all_lwps): ...this.

	* linux-low.h (class linux_process_target)
	<handle_extended_wait>
	<maybe_move_out_of_jump_pad>
	filter_event>
	<wait_for_event_filtered>
	<wait_for_event>
	<wait_1>
	<wait_for_sigstop>
	<move_out_of_jump_pad>
	<stop_all_lwps>
	<start_step_over>
	<complete_ongoing_step_over>
	<proceed_all_lwps>
	<unstop_all_lwps>: Declare.

	Update the callers below.

	* linux-low.cc (linux_process_target::attach): Update.
	(linux_process_target::stabilize_threads): Ditto.
	(linux_process_target::wait): Ditto.