Workaround for gcc/45682.

	Workaround for gcc/45682.
	* dwarf2read.c (partial_die_info): New fields fixup_called,
	linkage_name.
	(guess_partial_die_structure_name): Renamed from guess_structure_name.
	Move definition next to use.  Use linkage_name to determine if class
	is in a namespace.  All callers updated.
	(fixup_partial_die): Return early if already called.
	Set fixup_called when done.
	(guess_full_die_structure_name): New function.
	(determine_prefix): Call it for class/struct/union dies if c++ and
	.debug_types section is present and parent is DW_TAG_compile_unit.