Avoid warning on 32bit

On 32bit arches where time_t is defined as long int and where
sizeof(long)==sizeof(int), PRI_TIME is PRIu32 which is "u" and gcc warns about
ignoring the long part of the integer type. There is no problem besides the
warning.

Use "lu" in the above conditions and PRIu32 in all other 32bit time_t cases.

udevadm-monitor.c: In function ‘print_device’:
udevadm-monitor.c:49:16: warning: format ‘%u’ expects argument of type ‘unsigned int’, but argument 3 has type ‘__time_t’ {aka ‘long int’} [-Wformat=]
   49 |         printf("%-6s[%"PRI_TIME".%06ld] %-8s %s (%s)\n",
      |                ^~~~~~~~
   50 |                source,
   51 |                ts.tv_sec, ts.tv_nsec/1000,
      |                ~~~~~~~~~
      |                  |
      |                  __time_t {aka long int}
In file included from ../../src/shared/macro.h:26,
                 from udev.h:26,
                 from udevadm-monitor.c:35:
/usr/include/inttypes.h:104:19: note: format string is defined here
  104 | # define PRIu32  "u"

configure.ac

@@ -79,6 +79,7 @@ AC_CHECK_SIZEOF(pid_t)
 AC_CHECK_SIZEOF(uid_t)
 AC_CHECK_SIZEOF(gid_t)
 AC_CHECK_SIZEOF(dev_t)
+AC_CHECK_SIZEOF(long)
 AC_CHECK_SIZEOF(time_t)
 AC_CHECK_SIZEOF(rlim_t,,[[
 #include <sys/time.h>

src/shared/formats-util.h

@@ -49,7 +49,11 @@
 #if SIZEOF_TIME_T == 8
 #  define PRI_TIME PRIi64
 #elif SIZEOF_TIME_T == 4
-#  define PRI_TIME PRIu32
+#    if SIZEOF_LONG == 4
+#      define PRI_TIME "lu"
+#    else
+#      define PRI_TIME PRIu32
+#    endif
 #else
 #  error Unknown time_t size
 #endif