PR25648, objcopy SIGSEGV in ihex_write_record

ihex_set_section_contents sorts records stored on the tdata.ihex_data
list by address, but ihex_write_object_contents went too far in
assuming they were not overlapping.  This patch fixes the problem by
not assuming anything about addresses in ihex_write_object_contents.

	PR 25648
	* ihex.c (ihex_write_object_contents): Don't assume ordering of
	addresses here.  Remove dead code.