AArch64: Add attributes according to flags in built-in functions [PR94442]

2020-07-31  Zhiheng Xie  <xiezhiheng@huawei.com>

gcc/ChangeLog:

	* config/aarch64/aarch64-builtins.c (aarch64_general_add_builtin):
	Add new argument ATTRS.
	(aarch64_call_properties): New function.
	(aarch64_modifies_global_state_p): Likewise.
	(aarch64_reads_global_state_p): Likewise.
	(aarch64_could_trap_p): Likewise.
	(aarch64_add_attribute): Likewise.
	(aarch64_get_attributes): Likewise.
	(aarch64_init_simd_builtins): Add attributes for each built-in function.