aarch64: Add CPU-specific SVE vector costs struct

aarch64: Add CPU-specific SVE vector costs struct

This patch extends the backend vector costs structures to allow for
separate Advanced SIMD and SVE
costs. The fields in the current cpu_vector_costs that would vary
between the ISAs are moved into
a simd_vec_cost struct and we have two typedefs of it: advsimd_vec_cost
and sve_vec_costs.
If, in the future, SVE needs some extra fields it could inherit from
simd_vec_cost.
The CPU vector cost tables in aarch64.c are updated for the struct
changes.
aarch64_builtin_vectorization_cost is updated to select either the
Advanced SIMD or SVE costs field
depending on the mode and field availability.
No change in codegen is intended with this patch.

gcc/
	* config/aarch64/aarch64-protos.h (cpu_vector_cost): Move simd
	fields to...
	(simd_vec_cost): ... Here.  Define.
	(advsimd_vec_cost): Define.
	(sve_vec_cost): Define.
	* config/aarch64/aarch64.c (generic_advsimd_vector_cost):
	Define.
	(generic_sve_vector_cost): Likewise.
	(generic_vector_cost): Update.
	(qdf24xx_advsimd_vector_cost): Define.
	(qdf24xx_vector_cost): Update.
	(thunderx_advsimd_vector_cost): Define.
	(thunderx_vector_cost): Update.
	(tsv110_advsimd_vector_cost): Define.
	(tsv110_vector_cost): Likewise.
	(cortexa57_advsimd_vector_cost): Define.
	(cortexa57_vector_cost): Update.
	(exynosm1_advsimd_vector_cost): Define.
	(exynosm1_vector_cost): Update.
	(xgene1_advsimd_vector_cost): Define.
	(xgene1_vector_cost): Update.
	(thunderx2t99_advsimd_vector_cost): Define.
	(thunderx2t99_vector_cost): Update.
	(thunderx3t110_advsimd_vector_cost): Define.
	(thunderx3t110_vector_cost): Update.
	(aarch64_builtin_vectorization_cost): Handle sve and advsimd
	vector cost fields.