Sanitize printf format specifiers

[urbasus]

• Add have incorrect printf format specifier-parameter pairs generate compile-time warnings for printf-like functions.
  • SLPDLog and SLPDFatal.
• Fix warnings.

Warnings fixed, x64:

gcc -DHAVE_CONFIG_H -I. -I.. -I../common -I../libslpattr -I. -I../libslp -DETCDIR=\"/usr/local/etc\" -DVARDIR=\"/usr/local/var\"  -DLINUX  -g -O2 -Wall  -O2 -MT slpd_log.o -MD -MP -MF .deps/slpd_log.Tpo -c -o slpd_log.o slpd_log.c
slpd_log.c: In function ‘SLPDLogMessageInternals’:
slpd_log.c:356:26: warning: format ‘%i’ expects argument of type ‘int’, but argument 2 has type ‘size_t’ {aka ‘long unsigned int’} [-Wformat=]
  356 |    SLPDLog("   length = %i\n", message->header.length);
      |                         ~^     ~~~~~~~~~~~~~~~~~~~~~~
      |                          |                    |
      |                          int                  size_t {aka long unsigned int}
      |                         %li
slpd_log.c: In function ‘SLPDLogParseWarning’:
slpd_log.c:584:29: warning: format ‘%i’ expects argument of type ‘int’, but argument 2 has type ‘long int’ [-Wformat=]
  584 |    SLPDLog("message size = %i\n",buf->end - buf->start);
      |                            ~^    ~~~~~~~~~~~~~~~~~~~~~
      |                             |             |
      |                             int           long int
      |                            %li

x86:

gcc -DHAVE_CONFIG_H -I. -I.. -I../common -I../libslpattr -I. -I../libslp -DETCDIR=\"/usr/local/etc\" -DVARDIR=\"/usr/local/var\"  -DLINUX  -m32 -MT slpd_database.o -MD -MP -MF .deps/slpd_database.Tpo -c -o slpd_database.o slpd_database.c
slpd_database.c: In function ‘SLPDDatabaseReg’:
slpd_database.c:432:47: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 3 has type ‘unsigned int’ [-Wformat=]
  432 |          fprintf(stderr, "iface_addr malloc(%lu) failed\n",
      |                                             ~~^
      |                                               |
      |                                               long unsigned int
      |                                             %u
  433 |             slp_max_ifaces * sizeof(struct sockaddr_storage));
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                            |
      |                            unsigned int
slpd_database.c:440:47: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 3 has type ‘unsigned int’ [-Wformat=]
  440 |          fprintf(stderr, "bcast_addr malloc(%lu) failed\n",
      |                                             ~~^
      |                                               |
      |                                               long unsigned int
      |                                             %u
  441 |             slp_max_ifaces * sizeof(struct sockaddr_storage));
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                            |
      |                            unsigned int