Fix seg-faults when running readelf on fuzzed binaries.

	PR binutils/20440
	* dwarf.c (display_debug_lines_decoded): Add checks for running
	off the end of the section when populating the directory table and
	file table.
	(frame_display_row): Set max_regs equal to ncols.
	(load_specific_debug_section): If the section is compressed, but
	it is not big enough to hold a compression header then warn and
	return 0.