Remove 'step' parameters from 'proceed' and 'resume'

Remove 'step' parameters from 'proceed' and 'resume'

The "step" parameters of 'proceed' and 'resume' aren't really useful
as indication of whether run control wants to single-step the target,
as that information must already be retrievable from
currently_stepping.  In fact, if currently_stepping disagrees with
whether we single-stepped the target, then things break.  Thus instead
of having the same information in two places, this patch removes those
parameters.

Setting 'step_start_function' is the only user of proceed's 'step'
argument, other than passing the 'step' argument down to 'resume' and
debug log output.  Move that instead to set_step_frame, where we
already set other related fields.

clear_proceed_status keeps its "step" parameter for now because it
needs to know which set of threads should have their state cleared,
and is called before the "stepping_command" flag is set.

Tested on x86_64 Fedora 20, native and gdbserver.

gdb/ChangeLog:
2015-03-24  Pedro Alves  <palves@redhat.com>

	* breakpoint.c (until_break_command): Adjust call to proceed.
	* gdbthread.h (struct thread_control_state) <stepping_command>:
	New field.
	* infcall.c (run_inferior_call): Adjust call to proceed.
	* infcmd.c (run_command_1, proceed_thread_callback, continue_1):
	Adjust calls to proceed.
	(set_step_frame): Set the current thread's step_start_function
	here.
	(step_once): Adjust calls to proceed.
	(jump_command, signal_command, until_next_command)
	(finish_backward, finish_forward, proceed_after_attach_callback)
	(attach_command_post_wait): Adjust calls to proceed.
	* infrun.c (proceed_after_vfork_done): Adjust call to proceed.
	(do_target_resume): New function, factored out from ...
	(resume): ... here.  Remove 'step' parameter.  Instead, check
	currently_stepping to determine whether the thread should be
	single-stepped.
	(proceed): Remove 'step' parameter and don't set the thread's
	step_start_function here.  Adjust call to 'resume'.
	(handle_inferior_event): Adjust calls to 'resume'.
	(switch_back_to_stepped_thread): Use do_target_resume instead of
	'resume'.
	(keep_going): Adjust calls to 'resume'.
	* infrun.h (proceed): Remove 'step' parameter.
	(resume): Likewise.
	* windows-nat.c (do_initial_windows_stuff): Adjust call to
	'resume'.
	* mi/mi-main.c (proceed_thread): Adjust call to 'proceed'.