* Makefile.in (mips-tdep.o, target-descriptions.o): Update.
* target-descriptions.c (struct property): New.
(struct target_desc): Add properties member.
(tdesc_property, set_tdesc_property): New.
* target-descriptions.h (tdesc_property, set_tdesc_property):
Declare.
* mips-tdep.c (PROPERTY_GP32, PROPERTY_GP64): New constants.
(struct gdbarch_tdep): Add register_size_valid_p and register_size.
(mips_isa_regsize): Use them.
(mips_register_g_packet_guesses): New.
(mips_gdbarch_init): Call it. If a target description is supplied,
check for internal properties. Check for register size mismatches.
* remote.c (send_g_packet, process_g_packet): New functions, split
out from fetch_registers_using_g.
(fetch_registers_using_g): Use them.
(struct remote_g_packet_guess, remote_g_packet_guess_s)
(struct remote_g_packet_data, remote_g_packet_data_handle)
(remote_g_packet_data_init, register_remote_g_packet_guess)
(remote_read_description): New.
(init_remote_ops, init_remote_async_ops): Set to_read_description.
(_initialize_remote): Register remote_g_packet_data_handle.
* remote.h (register_remote_g_packet_guess): Declare.