PR python/17364

PR python/17364

gdb/ChangeLog:

	* python/lib/gdb/__init__.py (packages): Add "printer".
	* python/lib/gdb/command/bound_registers.py: Moved to ...
	* python/lib/gdb/printer/bound_registers.py: ... here.
	Add printer to global set of builtin printers.  Rename printer from
	"bound" to "mpx_bound128".
	* python/lib/gdb/printing.py (_builtin_pretty_printers): New global,
	registered as global "builtin" printer.
	(add_builtin_pretty_printer): New function.
	* data-directory/Makefile.in (PYTHON_FILE_LIST): Update, and add
	gdb/printer/__init__.py.