aarch64: Record separate streaming and non-streaming ISA requirements

aarch64: Record separate streaming and non-streaming ISA requirements

For some upcoming extensions, we need to add intrinsics whose
ISA requirements differ between streaming mode and non-streaming mode.
This patch tries to generalise the infrastructure to support that:

- Rather than have a single set of feature flags, the patch uses a
  separate set for sm_off (non-streaming, PSTATE.SM==0) and sm_on
  (streaming, PSTATE.SM==1).

- The sm_off set is zero if the intrinsic is streaming-only.
  Otherwise it is AARCH64_FL_SM_OFF | <requirements>.

- Similarly, the sm_on set is zero if the intrinsic is non-streaming-only.
  Otherwise it is AARCH64_FL_SM_ON | <requirements>.  AARCH64_FL_SME is
  taken as given in streaming mode.

- Streaming-compatible code must satisfy both sets of requirements.

There should be no functional change.

gcc/
	* config.gcc (aarch64*-*-*): Add aarch64-protos.h to target_gtfiles.
	* config/aarch64/aarch64-protos.h
	(aarch64_required_extensions): New structure.
	(aarch64_check_required_extensions): Change the type of the
	required_extensions parameter from aarch64_feature_flags to
	aarch64_required_extensions.
	* config/aarch64/aarch64-sve-builtins.h
	(function_builder::add_unique_function): Likewise.
	(function_builder::add_overloaded_function): Likewise.
	(function_builder::get_attributes): Likewise.
	(function_builder::add_function): Likewise.
	(function_group_info): Change the type of required_extensions
	in the same way.
	* config/aarch64/aarch64-builtins.cc
	(aarch64_pragma_builtins_data::required_extensions): Change the type
	from aarch64_feature_flags to aarch64_required_extensions.
	(aarch64_check_required_extensions): Likewise change the type
	of the required_extensions parameter.  Separate the requirements
	for non-streaming mode and streaming mode, ORing them together
	for streaming-compatible mode.
	(aarch64_general_required_extensions): New function.
	(aarch64_general_check_builtin_call): Use it.
	* config/aarch64/aarch64-sve-builtins.cc
	(registered_function::required_extensions): Change the type
	from aarch64_feature_flags to aarch64_required_extensions.
	(DEF_NEON_SVE_FUNCTION, DEF_SME_ZA_FUNCTION_GS): Update accordingly.
	(function_builder::get_attributes): Change the type of the
	required_extensions parameter from aarch64_feature_flags to
	aarch64_required_extensions.
	(function_builder::add_function): Likewise.
	(function_builder::add_unique_function): Likewise.
	(function_builder::add_overloaded_function): Likewise.
	* config/aarch64/aarch64-simd-pragma-builtins.def: Update
	REQUIRED_EXTENSIONS definitions to use aarch64_required_extensions.
	* config/aarch64/aarch64-sve-builtins-base.def: Likewise.
	* config/aarch64/aarch64-sve-builtins-sme.def: Likewise.
	* config/aarch64/aarch64-sve-builtins-sve2.def: Likewise.