Correct removal of .gnu.attributes
    
    Setting SEC_EXCLUDE for empty .gnu.attributes is too late in the link
    process for the linker to remove the section.  That must be done in
    bfd_elf_final_link, as we do for removed group sections.
    
    	* elflink.c (bfd_elf_final_link): Remove zero size .gnu.attributes
    	sections.
    
    (cherry picked from commit b8a6ced79668ec8af3180e50b76f7517ebbab0d9)