aarch64: Use an array of aarch64_vec_op_counts

aarch64: Use an array of aarch64_vec_op_counts

-mtune=neoverse-512tvb uses two issue rates, one for Neoverse V1
and one with more generic parameters.  We use both rates when
making a choice between scalar, Advanced SIMD and SVE code.

Previously we calculated the Neoverse V1 issue rates from the
more generic issue rates, but by removing m_scalar_ops and
(later) m_advsimd_ops, it becomes easier to track multiple
issue rates directly.

This patch therefore converts m_ops and (temporarily) m_advsimd_ops
into arrays.

gcc/
	* config/aarch64/aarch64.c (aarch64_vec_op_count): Allow default
	initialization.
	(aarch64_vec_op_count::base_issue_info): Remove handling of null
	issue_infos.
	(aarch64_vec_op_count::simd_issue_info): Likewise.
	(aarch64_vec_op_count::sve_issue_info): Likewise.
	(aarch64_vector_costs::m_ops): Turn into a vector.
	(aarch64_vector_costs::m_advsimd_ops): Likewise.
	(aarch64_vector_costs::aarch64_vector_costs): Add entries to
	the vectors based on aarch64_tune_params.
	(aarch64_vector_costs::analyze_loop_vinfo): Update the pred_ops
	of all entries in m_ops.
	(aarch64_vector_costs::add_stmt_cost): Call count_ops for all
	entries in m_ops.
	(aarch64_estimate_min_cycles_per_iter): Remove issue_info
	parameter and get the information from the ops instead.
	(aarch64_vector_costs::adjust_body_cost_sve): Take a
	aarch64_vec_issue_info instead of a aarch64_vec_op_count.
	(aarch64_vector_costs::adjust_body_cost): Update call accordingly.
	Exit earlier if m_ops is empty for either cost structure.