gdb/

gdb/
	* gdbint.texinfo (Target Vector Definition): Move most
	content into Existing Targets.  Add a menu.
	(Existing Targets): New section, moved from Target Vector
	Definition.  Use @subsection.
	(Managing Execution State): New section.
gdb/doc/
	* remote-sim.c (gdbsim_kill): Call target_mourn_inferior.
	(gdbsim_load): Don't bother to adjust inferior_ptid here.
	(gdbsim_create_inferior): Mark the simulator as running.
	(gdbsim_open): Don't bother fetching registers.  Mark
	the target as not running.
	(gdbsim_xfer): When the program is not running, pass memory
	requests down.
	(gdbsim_mourn_inferior): Mark the target as not running.
	* target.c (target_mark_running, target_mark_exited): New.
	* target.h (target_has_execution): Update the comment.
	(target_mark_running, target_mark_exited): New prototypes.