rs6000: Remove new_builtins_are_live and dead code it was guarding

To allow for a sane switch-over from the old built-in infrastructure to the
new, both sets of code have co-existed, with the enabled one under the control
of the boolean variable new_builtins_are_live.  As a first step in removing the
old code, remove this variable and the now-dead code it was guarding.

2021-12-06  Bill Schmidt  <wschmidt@linux.ibm.com>

gcc/
	* config/rs6000/darwin.h (SUBTARGET_INIT_BUILTINS): Remove
	test for new_builtins_are_live and simplify.
	* config/rs6000/rs6000-c.c (altivec_build_resolved_builtin): Remove
	dead function.
	(altivec_resolve_overloaded_builtin): Remove test for
	new_builtins_are_live and simplify.
	* config/rs6000/rs6000-call.c (altivec_init_builtins): Remove forward
	declaration.
	(builtin_function_type): Likewise.
	(rs6000_common_init_builtins): Likewise.
	(htm_init_builtins): Likewise.
	(mma_init_builtins): Likewise.
	(def_builtin): Remove dead function.
	(rs6000_expand_zeroop_builtin): Likewise.
	(rs6000_expand_mtfsf_builtin): Likewise.
	(rs6000_expand_mtfsb_builtin): Likewise.
	(rs6000_expand_set_fpscr_rn_builtin): Likewise.
	(rs6000_expand_set_fpscr_drn_builtin): Likewise.
	(rs6000_expand_unop_builtin): Likewise.
	(altivec_expand_abs_builtin): Likewise.
	(rs6000_expand_binop_builtin): Likewise.
	(altivec_expand_lxvr_builtin): Likewise.
	(altivec_expand_lv_builtin): Likewise.
	(altivec_expand_stxvl_builtin): Likewise.
	(altivec_expand_stv_builtin): Likewise.
	(mma_expand_builtin): Likewise.
	(htm_expand_builtin): Likewise.
	(cpu_expand_builtin): Likewise.
	(rs6000_expand_quaternop_builtin): Likewise.
	(rs6000_expand_ternop_builtin): Likewise.
	(altivec_expand_dst_builtin): Likewise.
	(altivec_expand_vec_sel_builtin): Likewise.
	(altivec_expand_builtin): Likewise.
	(rs6000_invalid_builtin): Likewise.
	(rs6000_builtin_valid_without_lhs): Likewise.
	(rs6000_gimple_fold_builtin): Remove test for new_builtins_are_live and
	simplify.
	(rs6000_expand_builtin): Likewise.
	(rs6000_init_builtins): Remove tests for new_builtins_are_live and
	simplify.
	(rs6000_builtin_decl): Likewise.
	(altivec_init_builtins): Remove dead function.
	(mma_init_builtins): Likewise.
	(htm_init_builtins): Likewise.
	(builtin_quaternary_function_type): Likewise.
	(builtin_function_type): Likewise.
	(rs6000_common_init_builtins): Likewise.
	* config/rs6000/rs6000-gen-builtins.c (write_header_file): Don't
	declare new_builtins_are_live.
	(write_init_bif_table): In generated code, remove test for
	new_builtins_are_live and simplify.
	(write_init_ovld_table): Likewise.
	(write_init_file): Don't initialize new_builtins_are_live.
	* config/rs6000/rs6000.c (rs6000_builtin_vectorized_function): Remove
	test for new_builtins_are_live and simplify.
	(rs6000_builtin_md_vectorized_function): Likewise.
	(rs6000_builtin_reciprocal): Likewise.
	(add_condition_to_bb): Likewise.
	(rs6000_atomic_assign_expand_fenv): Likewise.