buffer overflow in score_elf_create_dynamic_relocation

score_elf_create_dynamic_relocation sets up three output dynamic
relocs from rel[0], rel[1] and rel[2].  When rel[0] is the last reloc
in a section this of course results in a buffer overflow.  It's a
weird thing to do given that only one relocation is output.

	* elf32-score.c (score_elf_create_dynamic_relocation): Do not
	set up three dynamic relocations when only one is output.
	* elf32-score7.c: Likewise.