aarch64,arm: Move branch-protection data to targets

aarch64,arm: Move branch-protection data to targets

The branch-protection types are target specific, not the same on arm
and aarch64.  This currently affects pac-ret+b-key, but there will be
a new type on aarch64 that is not relevant for arm.

After the move, change aarch_ identifiers to aarch64_ or arm_ as
appropriate.

Refactor aarch_validate_mbranch_protection to take the target specific
branch-protection types as an argument.

In case of invalid input currently no hints are provided: the way
branch-protection types and subtypes can be mixed makes it difficult
without causing confusion.

gcc/ChangeLog:

	* config/aarch64/aarch64.md: Rename aarch_ to aarch64_.
	* config/aarch64/aarch64.opt: Likewise.
	* config/aarch64/aarch64-c.cc (aarch64_update_cpp_builtins): Likewise.
	* config/aarch64/aarch64.cc (aarch64_expand_prologue): Likewise.
	(aarch64_expand_epilogue): Likewise.
	(aarch64_post_cfi_startproc): Likewise.
	(aarch64_handle_no_branch_protection): Copy and rename.
	(aarch64_handle_standard_branch_protection): Likewise.
	(aarch64_handle_pac_ret_protection): Likewise.
	(aarch64_handle_pac_ret_leaf): Likewise.
	(aarch64_handle_pac_ret_b_key): Likewise.
	(aarch64_handle_bti_protection): Likewise.
	(aarch64_override_options): Update branch protection validation.
	(aarch64_handle_attr_branch_protection): Likewise.
	* config/arm/aarch-common-protos.h (aarch_validate_mbranch_protection):
	Pass branch protection type description as argument.
	(struct aarch_branch_protect_type): Move from aarch-common.h.
	* config/arm/aarch-common.cc (aarch_handle_no_branch_protection):
	Remove.
	(aarch_handle_standard_branch_protection): Remove.
	(aarch_handle_pac_ret_protection): Remove.
	(aarch_handle_pac_ret_leaf): Remove.
	(aarch_handle_pac_ret_b_key): Remove.
	(aarch_handle_bti_protection): Remove.
	(aarch_validate_mbranch_protection): Pass branch protection type
	description as argument.
	* config/arm/aarch-common.h (enum aarch_key_type): Remove.
	(struct aarch_branch_protect_type): Remove.
	* config/arm/arm-c.cc (arm_cpu_builtins): Remove aarch_ra_sign_key.
	* config/arm/arm.cc (arm_handle_no_branch_protection): Copy and rename.
	(arm_handle_standard_branch_protection): Likewise.
	(arm_handle_pac_ret_protection): Likewise.
	(arm_handle_pac_ret_leaf): Likewise.
	(arm_handle_bti_protection): Likewise.
	(arm_configure_build_target): Update branch protection validation.
	* config/arm/arm.opt: Remove aarch_ra_sign_key.