PR bootstrap/41405
	* dwarf2out.c (base_type_die, record_type_tag, gen_subprogram_die,
	add_call_src_coords_attributes, add_high_low_attributes,
	gen_compile_unit_die, gen_type_die_with_usage force_decl_die,
	gen_decl_die, dwarf2out_imported_module_or_decl_1, dwarf2out_finish,
	dwarf2out_imported_module_or_decl): Avoid using DWARF3 additions
	when -gdwarf-2 -gstrict-dwarf.
	(loc_list_from_tree): Likewise.  Avoid using DWARF4 additions when
	-gdwarf-[23] -gstrict-dwarf.
	(address_of_int_loc_descriptor, loc_descriptor,
	loc_list_for_address_of_addr_expr_of_indirect_ref): Avoid using
	DWARF4 additions when -gdwarf-[23] -gstrict-dwarf.
	* common.opt (gno-strict-dwarf, gstrict-dwarf): New options.

	* gfortran.dg/debug/pr37738.f: Add -gno-strict-dwarf to dg-options.
	* gfortran.dg/debug/pr35154-dwarf2.f: Likewise.
	* g++.dg/debug/dwarf2/explicit-constructor.C: Likewise.
	* g++.dg/debug/dwarf2/imported-module-2.C: Likewise.
	* g++.dg/debug/dwarf2/imported-module-3.C: Likewise.
	* g++.dg/debug/dwarf2/imported-module-4.C: Likewise.
	* g++.dg/debug/dwarf2/namespace-1.C: Likewise.
	* objc.dg/dwarf-2.m: Likewise.

From-SVN: r151978