RESP3: put RESP version in the client structure.

src/networking.c

@@ -107,6 +107,7 @@ client *createClient(int fd) {
     uint64_t client_id;
     atomicGetIncr(server.next_client_id,client_id,1);
     c->id = client_id;
+    c->resp = 2;
     c->fd = fd;
     c->name = NULL;
     c->bufpos = 0;

src/server.h

@@ -712,6 +712,7 @@ typedef struct readyList {
 typedef struct client {
     uint64_t id;            /* Client incremental unique ID. */
     int fd;                 /* Client socket. */
+    int resp;               /* RESP protocol version. Can be 2 or 3. */
     redisDb *db;            /* Pointer to currently SELECTed DB. */
     robj *name;             /* As set by CLIENT SETNAME. */
     sds querybuf;           /* Buffer we use to accumulate client queries. */