build: 32-bit status_debug fix

[arowser]

FIx build error on 32bit system:

cc channeld/channeld.c
In file included from channeld/channeld.c:41:
channeld/channeld.c: In function ‘peer_reconnect’:
channeld/channeld.c:5149:15: error: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 6 has type ‘size_t’ {aka ‘unsigned int’} [-Werror=format=]
 5149 |  status_debug("Got reestablish commit=%"PRIu64" revoke=%"PRIu64
      |               ^~~~~~~~~~~~~~~~~~~~~~~~~~
./common/status.h:41:28: note: in definition of macro ‘status_debug’
   41 |  status_fmt(LOG_DBG, NULL, __VA_ARGS__)
      |                            ^~~~~~~~~~~
channeld/channeld.c:5150:23: note: format string is defined here
 5150 |        " inflights: %lu, active splices: %"PRIu32,
      |                     ~~^
      |                       |
      |                       long unsigned int
      |                     %u

[vincenzopalazzo]

ACK 98add9c