* arm-tdep.c: Include features/arm-with-m.c.

	* arm-tdep.c: Include features/arm-with-m.c.
	(arm_psr_thumb_bit): New.  Update all uses of CPSR_T to
	call this function.
	(arm_pc_is_thumb): Add a gdbarch argument.  Update all callers.
	Check is_m after force-mode.
	(arm_gdbarch_init): Check the binary before the target description.
	Add check for M profile attribute.  If we have an M-profile device,
	but no target register description, use arm-with-m.  Recognize the
	new org.gnu.gdb.arm.m-profile feature and its xpsr register.
	(_initialize_arm_tdep): Call initialize_tdesc_arm_with_m.
	* arm-tdep.h (XPSR_T): Define.
	(struct gdbarch_tdep): Add is_m member.
	* features/arm-m-profile.xml, features/arm-with-m.c,
	features/arm-with-m.xml: New files.

	doc/
	* gdb.texinfo (ARM Features): Document
	org.gnu.gdb.arm.m-profile.