convert to_decr_pc_after_break

convert to_decr_pc_after_break

This converts to_decr_pc_after_break to the new style of delegation,
removing forward_target_decr_pc_after_break.

2014-02-19  Tom Tromey  <tromey@redhat.com>

	* record-btrace.c (record_btrace_decr_pc_after_break): Delegate
	directly.
	* target-delegates.c: Rebuild.
	* target.h (struct target_ops) <to_decr_pc_after_break>: Use
	TARGET_DEFAULT_FUNC.
	* target.c (default_target_decr_pc_after_break): Rename from
	forward_target_decr_pc_after_break.  Simplify.
	(target_decr_pc_after_break): Rely on delegation.