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/rfc3315.c

@@ -39,8 +39,8 @@ static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbu
 static void log6_opts(int nest, unsigned int xid, void *start_opts, void *end_opts);
 static void log6_packet(struct state *state, char *type, struct in6_addr *addr, char *string);
 static void log6_quiet(struct state *state, char *type, struct in6_addr *addr, char *string);
-static void *opt6_find (void *opts, void *end, unsigned int search, unsigned int minsize);
-static void *opt6_next(void *opts, void *end);
+static void *opt6_find (uint8_t *opts, uint8_t *end, unsigned int search, unsigned int minsize);
+static void *opt6_next(uint8_t *opts, uint8_t *end);
 static unsigned int opt6_uint(unsigned char *opt, int offset, int size);
 static void get_context_tag(struct state *state, struct dhcp_context *context);
 static int check_ia(struct state *state, void *opt, void **endp, void **ia_option);
@@ -61,11 +61,11 @@ static void calculate_times(struct dhcp_context *context, unsigned int *min_time
 
 #define opt6_len(opt) ((int)(opt6_uint(opt, -2, 2)))
 #define opt6_type(opt) (opt6_uint(opt, -4, 2))
-#define opt6_ptr(opt, i) ((void *)&(((unsigned char *)(opt))[4+(i)]))
+#define opt6_ptr(opt, i) ((void *)&(((uint8_t *)(opt))[4+(i)]))
 
-#define opt6_user_vendor_ptr(opt, i) ((void *)&(((unsigned char *)(opt))[2+(i)]))
+#define opt6_user_vendor_ptr(opt, i) ((void *)&(((uint8_t *)(opt))[2+(i)]))
 #define opt6_user_vendor_len(opt) ((int)(opt6_uint(opt, -4, 2)))
-#define opt6_user_vendor_next(opt, end) (opt6_next(((void *) opt) - 2, end))
+#define opt6_user_vendor_next(opt, end) (opt6_next(((uint8_t *) opt) - 2, end))
  
 
 unsigned short dhcp6_reply(struct dhcp_context *context, int interface, char *iface_name,
@@ -107,11 +107,11 @@ unsigned short dhcp6_reply(struct dhcp_context *context, int interface, char *if
 static int dhcp6_maybe_relay(struct state *state, unsigned char *inbuff, size_t sz, 
 			     struct in6_addr *client_addr, int is_unicast, time_t now)
 {
-  void *end = inbuff + sz;
-  void *opts = inbuff + 34;
+  uint8_t *end = inbuff + sz;
+  uint8_t *opts = inbuff + 34;
   int msg_type = *inbuff;
   unsigned char *outmsgtypep;
-  void *opt;
+  uint8_t *opt;
   struct dhcp_vendor *vendor;
 
   /* if not an encapsulated relayed message, just do the stuff */
@@ -232,7 +232,7 @@ static int dhcp6_maybe_relay(struct state *state, unsigned char *inbuff, size_t
   
   for (opt = opts; opt; opt = opt6_next(opt, end))
     {
-      if (opt6_ptr(opt, 0) + opt6_len(opt) > end) 
+      if ((uint8_t *)opt6_ptr(opt, 0) + opt6_len(opt) > end)
         return 0;
      
       /* Don't copy MAC address into reply. */
@@ -1307,7 +1307,7 @@ static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbu
      reallocated. */
   ((unsigned char *)(daemon->outpacket.iov_base))[start_msg] = outmsgtype;
 
-  log6_opts(0, state->xid, daemon->outpacket.iov_base + start_opts, daemon->outpacket.iov_base + save_counter(-1));
+  log6_opts(0, state->xid, (uint8_t *)daemon->outpacket.iov_base + start_opts, (uint8_t *)daemon->outpacket.iov_base + save_counter(-1));
   
   return 1;
 
@@ -2093,7 +2093,7 @@ static void log6_packet(struct state *state, char *type, struct in6_addr *addr,
 	      string ? string : "");
 }
 
-static void *opt6_find (void *opts, void *end, unsigned int search, unsigned int minsize)
+static void *opt6_find (uint8_t *opts, uint8_t *end, unsigned int search, unsigned int minsize)
 {
   u16 opt, opt_len;
   void *start;
@@ -2120,7 +2120,7 @@ static void *opt6_find (void *opts, void *end, unsigned int search, unsigned int
     }
 }
 
-static void *opt6_next(void *opts, void *end)
+static void *opt6_next(uint8_t *opts, uint8_t *end)
 {
   u16 opt_len;