Fix illegal memory accesses trigeered when linking corrupt input files.
    
    	PR 23055
    	* aoutx.h (find_nearest_line): Check that the symbol name exists
    	and is long enough, before attempting to see if it is for a .o
    	file.
    	* hash.c (bfd_hash_hash): Add an assertion that the string is not
    	NULL.
    	* linker.c (bfd_link_hash_lookup): Fail if the table or string are
    	NULL.
    	(_bfd_generic_link_add_archive_symbols): Fail if an archive entry
    	has no name.