More fixes for assertion failures and out-of-bounds reads by readelf.

More fixes for assertion failures and out-of-bounds reads by readelf.

	PR binutils/17531
	* (ia64_process_unwind): Replace assertion with an error message.
	Add range checking for group section indicies.
	(hppa_process_unwind): Replace assertion with an error message.
	(process_syminfo): Likewise.
	(decode_arm_unwind_bytecode): Add range checking.
	(dump_section_as_strings): Add more string range checking.
	(display_tag_value): Likewise.
	(display_arm_attribute): Likewise.
	(display_gnu_attribute): Likewise.
	(display_tic6x_attribute): Likewise.
	(display_msp430x_attribute): Likewise.