* expr.c (struct expr_symbol_line): Define.

	* expr.c (struct expr_symbol_line): Define.
	(expr_symbol_lines): New static variable.
	(make_expr_symbol): Add entry to expr_symbol_lines.
	(expr_symbol_where): New function.
	* expr.h: Use extern on function declarations.
	(expr_symbol_where): Declare.
	* symbols.c (resolve_symbol_value): Try to use expr_symbol_where
	rather than printing the meaningless name of an expression
	symbol.