Add support for DWARF-5 and experimental two-level line number tables.

Add support for DWARF-5 and experimental two-level line number tables.

http://wiki.dwarfstd.org/index.php?title=TwoLevelLineTables

2015-01-06  Cary Coutant  <ccoutant@google.com>

binutils/
	* dwarf.c (struct State_Machine_Registers): Add discriminator,
	context, and subprogram.
	(reset_state_machine): Likewise.
	(logicals_table, logicals_allocated, logicals_count): New variables.
	(free_logicals): New function.
	(append_logical): New function.
	(process_extended_line_op): Add is_logical parameter.
	(fetch_indirect_line_string): New function.
	(DWARF2_LINE_EXPERIMENTAL_VERSION): New macro.
	(read_debug_line_header): Add pinitial_length_size, poffset_size
	parameters.  Update all callers.  Check for new line table versions.
	(display_directory_table_v4): New function, factored out from
	display_debug_lines_raw.
	(display_file_name_table_v4): Likewise.
	(display_dir_file_table_v5): New function.
	(display_line_program): New function, factored out from
	display_debug_lines_raw.
	(display_debug_lines_raw): Support new line table versions.
	(display_debug_lines_decoded): Add missing newline to warning.
	(display_debug_lines): Load .debug_line_str section.
	(debug_displays): Add .debug_line_str section.
	* dwarf.h (DWARF2_Internal_LineInfo): Add li_actuals_table_offset field.
	(dwarf_section_display_enum): Add line_str.
	* readelf.c (process_section_headers): Add .debug_line_str.