Allow wildcard aliases in --bridge-interface option

This is useful when using dnsmasq as DHCP server for a set of VMs
whose data is routed by the host instead of being bridged.  In this
scenario:

- There is an unbounded set of TAP interfaces that have no IP address
  at the host end.

- DHCP allocation is done from an IPv4 address range associated with a
  dummy interface.

- We run dnsmasq with --interface dummy --interface tap*
  --bind-dynamic, so that it listens on all the TAP interfaces, and
  --bridge-interface=dummy,tap*, so that it will allocate IP addresses
  via the TAP interfaces from the range associated with the dummy
  interface.

src/dnsmasq.h

@@ -1150,6 +1150,7 @@ void bump_maxfd(int fd, int *max);
 int read_write(int fd, unsigned char *packet, int size, int rw);
 
 int wildcard_match(const char* wildcard, const char* match);
+int wildcard_matchn(const char* wildcard, const char* match, int num);
 
 /* log.c */
 void die(char *message, char *arg1, int exit_code);