Fix PR ld/20995 for cris-linux
    
    	* elf32-cris.c (elf_cris_finish_dynamic_symbol): Remove now unused
    	local variable dynobj.
    
    	PR ld/20995
    	* elf32-cris.c (elf_cris_size_dynamic_sections): Handle sdynrelro.
    	(elf_cris_adjust_dynamic_symbol): Place variables copied into the
    	executable from read-only sections into sdynrelro.
    	(elf_cris_finish_dynamic_symbol): Select sreldynrelro for
    	dynamic relocs in sdynrelro.
    	(elf_backend_want_dynrelro): Define.