Pass modutil function state as a struct

This allows the type to change without changing it at the call sites.

include/maxscale/modutil.h

@@ -52,6 +52,15 @@ GWBUF*          modutil_create_mysql_err_msg(int             packet_number,
                                              const char      *statemsg,
                                              const char      *msg);
 
+/** Struct used for tracking the state inside the modutil functions */
+typedef struct
+{
+    uint8_t state;
+} modutil_state;
+
+/** Static initialization define for modutil_state */
+#define MODUTIL_STATE_INIT {0}
+
 /**
  * @brief Count the number of EOF and ERR packets in the buffer.
  *
@@ -59,19 +68,20 @@ GWBUF*          modutil_create_mysql_err_msg(int             packet_number,
  * whole packets. If partial packets are in the buffer, they are ignored.
  * The caller must handle the detection of partial packets in buffers.
  *
- * On the first invocation, the value pointed by @c skip should be set to false.
- * On all subsequent calls, for partial result sets, the function uses it to
- * store the internal state. When the value pointed by @c skip is set to true,
- * the next call must be done with only unprocessed packets in @c reply.
+ * Before the first invocation, the value pointed by the @c state parameter
+ * should be initialized with MODUTIL_STATE_INIT. All subsequent calls with a
+ * partially processed result set must be made with only unprocessed packets
+ * in @c reply.
  *
  * @param reply      Buffer to use
  * @param n_found    Number of previous found packets
- * @param more       Set to true of more results exist
- * @param skip       Internal state of the function used for handling large payloads.
+ * @param more       Set to true if more results exist
+ * @param state      Internal state of the function, NULL if the function is
+ *                   only called once per result set
  *
  * @return Total number of EOF and ERR packets including the ones already found
  */
-int modutil_count_signal_packets(GWBUF *reply, int n_found, bool* more, bool* skip);
+int modutil_count_signal_packets(GWBUF *reply, int n_found, bool* more, modutil_state* state);
 
 mxs_pcre2_result_t modutil_mysql_wildcard_match(const char* pattern, const char* string);