use strlcat in gopher i/o device

FossilOrigin-Name: 0c74bdf49042376340861baf1ec1f4155a775380fd50efb23bc1fa9ea6880834

interfaces/io_gopher.c

@@ -109,7 +109,7 @@ void gopher_fetch(char *host, CELL port, char *selector, CELL dest) {
   while (n > 0) {
     bzero(buffer,1025);
     n = read(sockfd,buffer,1024);
-    strcat(data, buffer);
+    strlcat(data, buffer, (128 * 1024) + 1);
   }
 
   close(sockfd);