Use rtx_expr_list for expr_status.x_forced_labels

Use rtx_expr_list for expr_status.x_forced_labels

gcc/
2014-08-27  David Malcolm  <dmalcolm@redhat.com>

	* function.h (struct expr_status): Strengthen field
	"x_forced_labels" from rtx to rtx_expr_list *.

	* cfgbuild.c (make_edges): Split local "x" into two locals,
	strengthening one from rtx to rtx_expr_list *, and using methods
	of said class.
	* dwarf2cfi.c (create_trace_edges): Split local "lab" out; within
	loop over forced_labels, introduce strengthen it from rtx to
	rtx_expr_list *, using methods to clarify the code.
	* jump.c (rebuild_jump_labels_1): Strengthen local "insn" from rtx
	to rtx_expr_list *, using methods of said class to clarify the
	code.
	* reload1.c (set_initial_label_offsets): Split local "x" into two
	per-loop variables, strengthening the first from rtx to
	rtx_expr_list * and using methods.

From-SVN: r214602