Remove use of deprecated_command_loop_hook from mi code.

Remove use of deprecated_command_loop_hook from mi code.

  https://sourceware.org/ml/gdb-patches/2013-08/msg00605.html

gdb/ChangeLog

	* mi/mi-interp.c (mi_command_loop): Change signature to match
	interp_command_loop_ftype.
	(mi1_command_loop): Remove.
	(mi2_command_loop): Remove.
	(mi3_command_loop): Remove.
	(mi_interpreter_resume): Remove setting of
	deprecated_command_loop_hook.
	(_initialize_mi_interp): Set mi_command_loop as the command loop
	callback.