Use the new unified protocol to send SELECT to slaves.

SELECT was still transmitted to slaves using the inline protocol, that
is conceived mostly for humans to type into telnet sessions, and is
notably not understood by redis-cli --slave.

Now the new protocol is used instead.

src/redis.c

@@ -1058,8 +1058,14 @@ void createSharedObjects(void) {
     shared.plus = createObject(REDIS_STRING,sdsnew("+"));
 
     for (j = 0; j < REDIS_SHARED_SELECT_CMDS; j++) {
+        char dictid_str[64];
+        int dictid_len;
+
+        dictid_len = ll2string(dictid_str,sizeof(dictid_str),j);
         shared.select[j] = createObject(REDIS_STRING,
-            sdscatprintf(sdsempty(),"select %d\r\n", j));
+            sdscatprintf(sdsempty(),
+                "*2\r\n$6\r\nSELECT\r\n$%d\r\n%s\r\n",
+                dictid_len, dictid_str));
     }
     shared.messagebulk = createStringObject("$7\r\nmessage\r\n",13);
     shared.pmessagebulk = createStringObject("$8\r\npmessage\r\n",14);

src/replication.c

@@ -61,8 +61,14 @@ void replicationFeedSlaves(list *slaves, int dictid, robj **argv, int argc) {
                 selectcmd = shared.select[dictid];
                 incrRefCount(selectcmd);
             } else {
+                char dictid_str[64];
+                int dictid_len;
+
+                dictid_len = ll2string(dictid_str,sizeof(dictid_str),dictid);
                 selectcmd = createObject(REDIS_STRING,
-                    sdscatprintf(sdsempty(),"select %d\r\n",dictid));
+                    sdscatprintf(sdsempty(),
+                        "*2\r\n$6\r\nSELECT\r\n$%d\r\n%s\r\n",
+                        dictid_len, dictid_str));
             }
             addReply(slave,selectcmd);
             decrRefCount(selectcmd);