Add a new breakpoint callback: on_continue

- called instead of continue_after_breakpoint, which remains the default
  action if the callback is not defined
diff --git a/breakpoint.h b/breakpoint.h
index ae4a2b8..c156d91 100644
--- a/breakpoint.h
+++ b/breakpoint.h
@@ -64,6 +64,7 @@
 
 struct bp_callbacks {
 	void (*on_hit) (struct breakpoint *bp, struct Process *proc);
+	void (*on_continue) (struct breakpoint *bp, struct Process *proc);
 	void (*on_destroy) (struct breakpoint *bp);
 };
 
@@ -79,6 +80,10 @@
 /* Call on-hit handler of BP, if any is set.  */
 void breakpoint_on_hit(struct breakpoint *bp, struct Process *proc);
 
+/* Call on-reenable handler of BP.  If none is set, call
+ * continue_after_breakpoint.  */
+void breakpoint_on_continue(struct breakpoint *bp, struct Process *proc);
+
 /* Initialize a breakpoint structure.  That doesn't actually realize
  * the breakpoint.  The breakpoint is initially assumed to be
  * disabled.  orig_value has to be set separately.  CBS may be