(arm_register_g_packet_guesses): New function.
(arm_gdbarch_init): Don't force a target description with
registers when the executable is detected as M-profile. Instead
set gdbarch->tdep->is_m. Register `g' packet guesses.
(_initialize_arm_tdep): Initialize the new target description.
* features/arm-with-m-fpa-layout.xml: New description.
* features/arm-with-m-fpa-layout.c: New, generated.
