Teach linux gdbserver to step-over-breakpoints.

* linux-low.c (can_hardware_single_step): New.
	(supports_breakpoints): New.
	(handle_extended_wait): If stopping threads, read the stop pc of
	the new cloned LWP.
	(get_pc): New.
	(get_stop_pc): Add `lwp' parameter.  Handle it.  Bail out if the
	low target doesn't support retrieving the PC.
	(add_lwp): Set last_resume_kind to resume_continue.
	(linux_attach_lwp_1): Adjust comments.  Always set stop_expected.
	(linux_attach): Don't clear stop_expected.  Set the lwp's
	last_resume_kind to resume_stop.
	(linux_detach_one_lwp): Don't check for removed breakpoints.
	(check_removed_breakpoint): Delete.
	(status_pending_p): Rename to ...
	(status_pending_p_callback): ... this.  Don't check for removed
	breakpoints.  Don't consider threads that are stopped from GDB's
	perspective.
	(linux_wait_for_lwp): Always read the stop_pc here.
	(cancel_breakpoint): New.
	(step_over_bkpt): New global.
	(linux_wait_for_event_1): Implement stepping over breakpoints.
	(gdb_wants_lwp_stopped): New.
	(gdb_wants_all_stopped): New.
	(linux_wait_1): Tag threads as gdb-wants-stopped.  Cancel finished
	single-step traps here.  Store the thread's last reported target
	wait status.
	(send_sigstop): Don't clear stop_expected.  Always set it,
	instead.
	(mark_lwp_dead): Remove reference to pending_is_breakpoint.
	(cancel_finished_single_step): New.
	(cancel_finished_single_steps): New.
	(wait_for_sigstop): Don't cancel finished single-step traps here.
	(linux_resume_one_lwp): Don't check for removed breakpoints.
	Don't set `step' on non-hardware step archs.
	(linux_set_resume_request): Ignore resume_stop requests if already
	stopping or stopped.  Set the lwp's last_resume_kind.
	(resume_status_pending_p): Don't check for removed breakpoints.
	(need_step_over_p): New.
	(start_step_over): New.
	(finish_step_over): New.
	(linux_resume_one_thread): Always queue a sigstop for resume_stop
	requests.  Clear the thread's last reported target waitstatus.
	Don't use the `suspended' flag.  Don't consider pending breakpoints.
	(linux_resume): Start a step-over if necessary.
	(proceed_one_lwp): New.
	(proceed_all_lwps): New.
	(unstop_all_lwps): New.
	* linux-low.h (struct lwp_info): Rewrite comment for the
	`suspended' flag.  Add the `stop_pc' field.  Delete the
	`pending_stop_pc' field.  Tweak the `stepping' flag's comment.
	Add `'last_resume_kind' and `need_step_over' fields.
	* inferiors.c (struct thread_info): Delete, moved elsewhere.
	* mem-break.c (struct breakpoint): Delete `reinserting' flag.
	Delete `breakpoint_to_reinsert' field.  New flag `inserted'.
	(set_raw_breakpoint_at): New.
	(set_breakpoint_at): Rewrite to use it.
	(reinsert_breakpoint_handler): Delete.
	(set_reinsert_breakpoint): New.
	(reinsert_breakpoint_by_bp): Delete.
	(delete_reinsert_breakpoints): New.
	(uninsert_breakpoint): Rewrite.
	(uninsert_breakpoints_at): New.
	(reinsert_breakpoint): Rewrite.
	(reinsert_breakpoints_at): New.
	(check_breakpoints): Rewrite.
	(breakpoint_here): New.
	(breakpoint_inserted_here): New.
	(check_mem_read): Adjust.
	* mem-break.h (breakpoints_supported, breakpoint_here)
	(breakpoint_inserted_here, set_reinsert_breakpoint): Declare.
	(reinsert_breakpoint_by_bp): Delete declaration.
	(delete_reinsert_breakpoints): Declare.
	(reinsert_breakpoint): Delete declaration.
	(reinsert_breakpoints_at): Declare.
	(uninsert_breakpoint): Delete declaration.
	(uninsert_breakpoints_at): Declare.
	(check_breakpoints): Adjust prototype.
	* server.h: Adjust include order.
	(struct thread_info): Declare here.  Add a `last_status' field.

gdb/gdbserver/server.h

@@ -162,8 +162,25 @@ struct inferior_list_entry
   struct inferior_list_entry *next;
 };
 
-/* Opaque type for user-visible threads.  */
 struct thread_info;
+struct process_info;
+struct regcache;
+
+#include "regcache.h"
+#include "gdb/signals.h"
+#include "gdb_signals.h"
+#include "target.h"
+#include "mem-break.h"
+
+struct thread_info
+{
+  struct inferior_list_entry entry;
+  void *target_data;
+  void *regcache_data;
+
+  /* The last wait status reported for this thread.  */
+  struct target_waitstatus last_status;
+};
 
 struct dll_info
 {
@@ -203,12 +220,6 @@ struct process_info
 struct process_info *current_process (void);
 struct process_info *get_thread_process (struct thread_info *);
 
-#include "regcache.h"
-#include "gdb/signals.h"
-#include "gdb_signals.h"
-#include "target.h"
-#include "mem-break.h"
-
 /* Target-specific functions */
 
 void initialize_low ();