PR ld/22832 on SPARC.
    
    The fix for PR ld/22727 on SPARC passed TRUE as the 'create' argument
    in the call to bfd_link_hash_lookup.  It turns out this was a bad idea
    because, if the symbol is created at this point, the link will abort
    later in elf_link_output_extsym.  This changes the TRUE into a FALSE
    and puts an assertion on the result of the call, making it easier to
    debug the issue; that's exactly in keeping with what Gold does.
    
    bfd/
    	* elfxx-sparc.c (_bfd_sparc_elf_check_relocs) <R_SPARC_TLS_GD_CALL>:
    	Pass FALSE instead of TRUE as 'create' argument to bfd_link_hash_lookup
    	and assert that the result of the call is not NULL.