MINOR: http-rule/tcp-rules: Make track-sc* custom actions

Now, these actions use their own dedicated function and are no longer handled
"in place" during the TCP/HTTP rules evaluation. Thus the action names
ACT_ACTION_TRK_SC0 and ACT_ACTION_TRK_SCMAX are removed. The action type is now
the tracking index. Thus the function trk_idx() is no longer needed.
diff --git a/include/proto/action.h b/include/proto/action.h
index d0b2c5d..b7339f4 100644
--- a/include/proto/action.h
+++ b/include/proto/action.h
@@ -72,15 +72,7 @@
 		*p = '\0';
 }
 
-/* for an action ACT_ACTION_TRK_SC*, return a tracking index starting at zero
- * for SC0. Unknown actions also return zero.
- */
-static inline int trk_idx(int trk_action)
-{
-	return trk_action - ACT_ACTION_TRK_SC0;
-}
-
-/* Find and check the target table used by an action ACT_ACTION_TRK_*. This
+/* Find and check the target table used by an action track-sc*. This
  * function should be called during the configuration validity check.
  *
  * The function returns 1 in success case, otherwise, it returns 0 and err is