non_ir_ref_dynamic

dynamic_ref_after_ir_def is a little odd compared to other symbol
flags in that as the name suggests, it is set only for certain
references after a definition.  It turns out that setting a flag for
any non-ir reference from a dynamic object can be used to solve the
problem for which this flag was invented, which I think is a cleaner.
This patch does that, and sets non_ir_ref only for regular object
references.

include/
	* bfdlink.h (struct bfd_link_hash_entry): Update non_ir_ref
	comment.  Rename dynamic_ref_after_ir_def to non_ir_ref_dynamic.
ld/
	* plugin.c (is_visible_from_outside): Use non_ir_ref_dynamic.
	(plugin_notice): Set non_ir_ref for references from regular
	objects, non_ir_ref_dynamic for references from dynamic objects.
bfd/
	* elf64-ppc.c (add_symbol_adjust): Transfer non_ir_ref_dynamic.
	* elflink.c (elf_link_add_object_symbols): Update to use
	non_ir_ref_dynamic.
	(elf_link_input_bfd): Test non_ir_ref_dynamic in addition to
	non_ir_ref.
	* linker.c (_bfd_generic_link_add_one_symbol): Likewise.

(cherry picked from commit 4070765b)