[arm][2/2] Remove support for -march=armv3 and older

[arm][2/2] Remove support for -march=armv3 and older

We deprecated architecture versions earlier than Armv4T in GCC 6 [1].
This patch removes support for architectures lower than Armv4.
That is the -march values armv2, armv2a, armv3, armv3m are removed
with this patch.  I did not remove armv4 because it's a bit more
involved code-wise and there has been some pushback on the implications
for -mcpu=strongarm support.

Removing armv3m and earlier though is pretty straightforward.
This allows us to get rid of the armv3m and mode32 feature bits
in arm-cpus.in as they can be assumed to be universally available.

Consequently the mcpu values arm2, arm250, arm3, arm6, arm60, arm600, arm610, arm620, arm7, arm7d, arm7di, arm70, arm700, arm700i, arm710, arm720, arm710c, arm7100, arm7500, arm7500fe, arm7m, arm7dm, arm7dm are now also removed.

Bootstrapped and tested on arm-none-linux-gnueabihf and on arm-none-eabi
with an aprofile multilib configuration (which builds quite a lot of library
configurations).

[1] https://gcc.gnu.org/gcc-6/changes.html#arm

	* config/arm/arm-cpus.in (armv3m, mode32): Delete features.
	(ARMv4): Update.
	(ARMv2, ARMv3, ARMv3m): Delete fgroups.
	(ARMv6m): Update.
	(armv2, armv2a, armv3, armv3m): Delete architectures.
	(arm2, arm250, arm3, arm6, arm60, arm600, arm610, arm620,
	arm7, arm7d, arm7di, arm70, arm700, arm700i, arm710, arm720,
	arm710c, arm7100, arm7500, arm7500fe, arm7m, arm7dm, arm7dmi):
	Delete cpus.
	* config/arm/arm.md (maddsidi4): Remove check for arm_arch3m.
	(*mulsidi3adddi): Likewise.
	(mulsidi3): Likewise.
	(*mulsidi3_nov6): Likewise.
	(umulsidi3): Likewise.
	(umulsidi3_nov6): Likewise.
	(umaddsidi4): Likewise.
	(*umulsidi3adddi): Likewise.
	(smulsi3_highpart): Likewise.
	(*smulsi3_highpart_nov6): Likewise.
	(umulsi3_highpart): Likewise.
	(*umulsi3_highpart_nov6): Likewise.
	* config/arm/arm.h (arm_arch3m): Delete.
	* config/arm/arm.c (arm_arch3m): Delete.
	(arm_option_override_internal): Update armv3-related comment.
	(arm_configure_build_target): Delete use of isa_bit_mode32.
	(arm_option_reconfigure_globals): Delete set of arm_ach3m.
	(arm_rtx_costs_internal): Delete check of arm_arch3m.
	* config/arm/arm-fixed.md (mulsq3): Delete check for arm_arch3m.
	(mulsa3): Likewise.
	(mulusa3): Likewise.
	* config/arm/arm-protos.h (arm_arch3m): Delete.
	* config/arm/arm-tables.opt: Regenerate.
	* config/arm/arm-tune.md: Likewise.
	* config/arm/t-arm-elf (all_early_nofp): Delete mentions of
	deleted architectures.

	* gcc.target/arm/pr62554.c: Delete.
	* gcc.target/arm/pr69610-1.c: Likewise.
	* gcc.target/arm/pr69610-2.c: Likewise.

From-SVN: r260363