Handle symbol defined in IR and referenced in DSO
    
    We need to make an IR symbol visible if it is defined in an IR object
    and referenced in a dynamic object.  When --as-needed is used, since
    linker removes the IR symbol reference of the dynamic object if the
    dynamic object isn't needed in the first pass, the IR definition isn't
    visible to the dynamic object even if the dynamic object becomes needed
    in the second pass.  Add dynamic_ref_after_ir_def to bfd_link_hash_entry
    to track IR symbol which is defined in an IR object and later referenced
    in a dynamic object.  dynamic_ref_after_ir_def is preserved when restoring
    the symbol table for unneeded dynamic object.
    
    bfd/
    
    	PR ld/21382
    	* elflink.c (elf_link_add_object_symbols): Preserve
    	dynamic_ref_after_ir_def when restoring the symbol table for
    	unneeded dynamic object.
    
    include/
    
    	PR ld/21382
    	* bfdlink.h (bfd_link_hash_entry): Add dynamic_ref_after_ir_def.
    
    ld/
    
    	PR ld/21382
    	* plugin.c (is_visible_from_outside): Symbol may be visible
    	from outside if dynamic_ref_after_ir_def is set.
    	(plugin_notice): Set dynamic_ref_after_ir_def if the symbol is
    	defined in an IR object and referenced in a dynamic object.
    	* testsuite/ld-plugin/lto.exp: Run PR ld/21382 tests.
    	* testsuite/ld-plugin/pr21382a.c: New file.
    	* testsuite/ld-plugin/pr21382b.c: Likewise.
    
    (cherry picked from commit 59fa66c53823dc695f78669f40ec2eebab3aec42)