Fix FTBFS when using -pedantic compiler flag.

I am attaching an incremental git-am ready patch to go on top your Git HEAD,
to fix all sorts of issues and make this conforming C99 with default
options set,
and fix another load of warnings you receive when setting the compiler
to pick the nits,
-pedantic-errors -std=c99 (or c11, c18, c2x).
It changes many void * to uint8_t * to make the "increment by bytes"
explicit.
You can't do:

void *foo;
// ...
foo += 2.

src/dnsmasq.h

@@ -339,7 +339,7 @@ union all_addr {
   struct datablock {
     unsigned short rrtype;
     unsigned char datalen; /* also length of SOA in negative records. */
-    char data[];
+    char data[1];
   } rrdata;
 };
 
@@ -1667,7 +1667,7 @@ void route_sock(void);
 
 /* bpf.c or netlink.c */
 typedef union {
-	int (*af_unspec)(int family, char *addrp, char *mac, size_t maclen, void *parmv);
+	int (*af_unspec)(int family, void *addrp, char *mac, size_t maclen, void *parmv);
 	int (*af_inet)(struct in_addr local, int if_index, char *label, struct in_addr netmask, struct in_addr broadcast, void *vparam);
 	int (*af_inet6)(struct in6_addr *local, int prefix, int scope, int if_index, int flags, unsigned int preferred, unsigned int valid, void *vparam);
 	int (*af_local)(int index, unsigned int type, char *mac, size_t maclen, void *parm);