aarch64: Check UNDEFWEAK_NO_DYNAMIC_RELOC

Don't generate dynamic relocation against weak undefined symbol if it
is resolved to zero.  FIXME: UNDEFWEAK_NO_DYNAMIC_RELOC may need to be
checked in more places.

	PR ld/22269
	* elfnn-aarch64.c (elfNN_aarch64_final_link_relocate): Don't
	generate dynamic relocation if UNDEFWEAK_NO_DYNAMIC_RELOC is
	true.
	(elfNN_aarch64_allocate_dynrelocs): Discard dynamic relocations
	if UNDEFWEAK_NO_DYNAMIC_RELOC is true.