This patch adds support for C23's _BitInt for the AArch64 port when compiling
for little endianness.  Big Endianness requires further target-agnostic
support and we therefor disable it for now.

gcc/ChangeLog:

	* config/aarch64/aarch64.cc (TARGET_C_BITINT_TYPE_INFO): Declare MACRO.
	(aarch64_bitint_type_info): New function.
	(aarch64_return_in_memory_1): Return large _BitInt's in memory.
	(aarch64_function_arg_alignment): Adapt to correctly return the ABI
	mandated alignment of _BitInt(N) where N > 128 as the alignment of
	TImode.
	(aarch64_composite_type_p): Return true for _BitInt(N), where N > 128.

libgcc/ChangeLog:

	* config/aarch64/t-softfp: Add fixtfbitint, floatbitinttf and
	floatbitinthf to the softfp_extras variable to ensure the
	runtime support is available for _BitInt.
---
 gcc/config/aarch64/aarch64.cc  | 44 +++++++++++++++++++++++++++++++++-
 libgcc/config/aarch64/t-softfp |  3 ++-
 2 files changed, 45 insertions(+), 2 deletions(-)