Fix error in expression evalutation in linker output maps.

Fix error in expression evalutation in linker output maps.

	PR 24008
	* ldexp.h (lang_phase_type): Add lang_fixed_phase_enum.
	* ldexp.c (fold_name): Move expld.assign_name check later to
	avoid an extra lookup.
	(exp_fold_tree_1): When lang_fixed_phase_enum, don't change symbol
	values, and don't clear expld.assign_name.
	* ldlang.c (lang_map): Set expld.phase to lang_fixed_phase_enum.
	(print_assignment): Resolve entire assignment expression.
	Don't access symbol u.def unless symbol is defined.