More fixes for invalid memory accesses triggered by fuzzed binaries.

More fixes for invalid memory accesses triggered by fuzzed binaries.

	PR binutils/17531
	* dwarf.c (display_debug_frames): Check for a negative
	augmentation data length.
	(display_gdb_index): Check for invalid offsets.
	* elfcomm.c (process_archive_index_and_symbols): Check for an
	index number that overflows when multiplied by the ar index size.
	* readelf.c (dump_ia64_unwind): Add range checks.
	(slurp_ia64_unwind_table): Change to a boolean function.  Add
	range checks.
	(process_version_sections): Add range checks.
	(get_symbol_version_string): Add check for missing section
	headers.