[arm] auto-generate arm-isa.h from CPU descriptions

[arm] auto-generate arm-isa.h from CPU descriptions

This patch autogenerates arm-isa.h from new entries in arm-cpus.in.
This has the primary advantage that it makes the description file more
self-contained, but it also solves the 'array dimensioning' problem
that Tamar recently encountered.  It adds two new constructs to
arm-cpus.in: features and fgroups.  Fgroups are simply a way of naming
a group of feature bits so that they can be referenced together.  We
follow the convention that feature bits are all lower case, while
fgroups are (predominantly) upper case. This is helpful as in some
contexts they share the same namespace. Most of the minor changes in
this patch are related to adopting this new naming convention.

2017-09-22  Richard Earnshaw  <richard.earnshaw@arm.com>

	* config.gcc (arm*-*-*): Don't add arm-isa.h to tm_p_file.
	* config/arm/arm-isa.h: Delete.  Move definitions to ...
	* arm-cpus.in: ... here.  Use new feature and fgroup values.
	* config/arm/arm.c (arm_option_override): Use lower case for feature
	bit names.
	* config/arm/arm.h (TARGET_HARD_FLOAT): Likewise.
	(TARGET_VFP3, TARGET_VFP5, TARGET_FMA): Likewise.
	* config/arm/parsecpu.awk (END): Add new command 'isa'.
	(isa_pfx): Delete.
	(print_isa_bits_for): New function.
	(gen_isa): New function.
	(gen_comm_data): Use print_isa_bits_for.
	(define feature): New keyword.
	(define fgroup): New keyword.
	* config/arm/t-arm (TM_H): Remove.
	(GTM_H): Add arm-isa.h.
	(arm-isa.h): Add rule to generate file.
	* common/config/arm/arm-common.c: (arm_canon_arch_option): Use lower
	case for feature bit names.

From-SVN: r253097