Remove --xdb

Pedro Alves:

The commands that enables aren't even documented in the manual.
Judging from that, I assume that only wdb users would ever really
be using the --xdb switch.

I think it's time to drop "support" for the --xdb switch too.  I
looked through the commands that that exposes, the only that looked
potentially interesting was "go", but then it's just an alias
for "tbreak+jump", which can easily be done with "define go...end".
I'd rather free up the "go" name for something potentially
more interesting (either run control, or maybe even unrelated,
e.g., for golang).

gdb/ChangeLog
2015-04-11  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* NEWS (Changes since GDB 7.9): Add removed -xdb.
	* breakpoint.c (command_line_is_silent): Remove xdb_commands
	conditional.
	(_initialize_breakpoint): Remove xdb_commands for bc, ab, sb, db, ba
	and lb.
	* cli/cli-cmds.c (_initialize_cli_cmds): Remove xdb_commands for v and
	va.
	* cli/cli-decode.c (find_command_name_length): Remove xdb_commands
	conditional.
	* defs.h (xdb_commands): Remove declaration.
	* f-valprint.c (_initialize_f_valprint): Remove xdb_commands for lc.
	* guile/scm-cmd.c (command_classes): Remove xdb from comment.
	* infcmd.c (run_no_args_command, go_command): Remove.
	(_initialize_infcmd): Remove xdb_commands for S, go, g, R and lr.
	* infrun.c (xdb_handle_command): Remove.
	(_initialize_infrun): Remove xdb_commands for lz and z.
	* main.c (xdb_commands): Remove variable.
	(captured_main): Remove "xdb" from long_options.
	(print_gdb_help): Remove --xdb from help.
	* python/py-cmd.c (gdbpy_initialize_commands): Remove xdb from comment.
	* source.c (_initialize_source): Remove xdb_commands for D, ld, / and ?.
	* stack.c (backtrace_full_command, args_plus_locals_info)
	(current_frame_command): Remove.
	(_initialize_stack): Remove xdb_commands for t, T and l.
	* symtab.c (_initialize_symtab): Remove xdb_commands for lf and lg.
	* thread.c (_initialize_thread): Remove xdb_commands condition.
	* tui/tui-layout.c (tui_toggle_layout_command)
	(tui_toggle_split_layout_command, tui_handle_xdb_layout): Remove.
	(_initialize_tui_layout): Remove xdb_commands for td and ts.
	* tui/tui-regs.c (tui_scroll_regs_forward_command)
	(tui_scroll_regs_backward_command): Remove.
	(_initialize_tui_regs): Remove xdb_commands for fr, gr, sr, +r and -r.
	* tui/tui-win.c (tui_xdb_set_win_height_command): Remove.
	(_initialize_tui_win): Remove xdb_commands for U and w.
	* utils.c (pagination_on_command, pagination_off_command): Remove.
	(initialize_utils): Remove xdb_commands for am and sm.

gdb/doc/ChangeLog
2015-04-11  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.texinfo (Mode Options): Remove -xdb.

gdb/python/py-cmd.c

@@ -682,7 +682,7 @@ gdbpy_initialize_commands (void)
     return -1;
 
   /* Note: alias and user are special; pseudo appears to be unused,
-     and there is no reason to expose tui or xdb, I think.  */
+     and there is no reason to expose tui, I think.  */
   if (PyModule_AddIntConstant (gdb_module, "COMMAND_NONE", no_class) < 0
       || PyModule_AddIntConstant (gdb_module, "COMMAND_RUNNING", class_run) < 0
       || PyModule_AddIntConstant (gdb_module, "COMMAND_DATA", class_vars) < 0