PR27441, inconsistency in weak definitions

This makes IR objects use the same logic as normal objects with
respect to what sort of ref/def makes an as-needed library needed.
Testing the binding of the definition is just plain wrong.  What
matters is the binding of the reference.

	PR 27441
	* elf-bfd.h (struct elf_link_hash_entry): Add ref_ir_nonweak.
	* elflink.c (elf_link_add_object_symbols): Set ref_ir_nonweak and
	use when deciding an as-needed library should be loaded instead
	of using the binding of the library definition.