Fix compiler warning and compatibility issue with the type of the parameter used in getnameinfo() to receive the length of the sockaddr struct.

ares.h

@@ -172,7 +172,7 @@ void ares_gethostbyname(ares_channel channel, const char *name, int family,
 void ares_gethostbyaddr(ares_channel channel, const void *addr, int addrlen,
                         int family, ares_host_callback callback, void *arg);
 void ares_getnameinfo(ares_channel channel, const struct sockaddr *sa,
-                      socklen_t salen, int flags, ares_nameinfo_callback callback,
+                      size_t salen, int flags, ares_nameinfo_callback callback,
                       void *arg);
 int ares_fds(ares_channel channel, fd_set *read_fds, fd_set *write_fds);
 struct timeval *ares_timeout(ares_channel channel, struct timeval *maxtv,

ares_getnameinfo.c

@@ -78,7 +78,7 @@ static void append_scopeid(struct sockaddr_in6 *addr6, unsigned int scopeid,
 #endif
 static char *ares_striendstr(const char *s1, const char *s2);
 
-void ares_getnameinfo(ares_channel channel, const struct sockaddr *sa, socklen_t salen,
+void ares_getnameinfo(ares_channel channel, const struct sockaddr *sa, size_t salen,
                       int flags, ares_nameinfo_callback callback, void *arg)
 {
   struct sockaddr_in *addr = NULL;