re PR debug/86456 (Segfault in switch_to_section at gcc/varasm.c:7353 since r259317)

re PR debug/86456 (Segfault in switch_to_section at  gcc/varasm.c:7353 since r259317)

2018-07-17  Richard Biener  <rguenther@suse.de>

	PR lto/86456
	* dwarf2out.c (init_sections_and_labels): Always generate
	a debug_line_str_section for early LTO debug.
	(dwarf2out_finish): Reset debug_line_str_hash output early.
	Bump counter for extra dwarf5 .debug_loc labels to not conflict
	with fat LTO part.
	(dwarf2out_early_finish): Output debug_line_str.

	* g++.dg/debug/dwarf2/pr86456.C: New testcase.

From-SVN: r262819