re PR debug/42454 (debug_ranges table contains empty range for unused .text section with -ffunction-sections)

	PR debug/42454
	* dwarf2out.c (add_ranges_by_labels_to_AT_range_list): New function.
	(dwarf2out_finish): Call add_ranges_by_labels_to_AT_range_list.

	* gcc.dg/debug/dwarf2/aranges-fnsec-1.c: Add check for .debug_ranges.

Co-Authored-By: Cary Coutant <ccoutant@google.com>

From-SVN: r155429