BITOP: propagate only when it really SET or DEL targetkey (#5783)

For example:
    BITOP not targetkey sourcekey

If targetkey and sourcekey doesn't exist, BITOP has no effect,
we do not propagate it, thus can save aof and replica flow.

(cherry picked from commit 1978f996d8b13db112d5d2fdf4a4ce2baf636729)

src/bitops.c

@@ -759,11 +759,12 @@ void bitopCommand(client *c) {
         setKey(c,c->db,targetkey,o);
         notifyKeyspaceEvent(NOTIFY_STRING,"set",targetkey,c->db->id);
         decrRefCount(o);
+        server.dirty++;
     } else if (dbDelete(c->db,targetkey)) {
         signalModifiedKey(c,c->db,targetkey);
         notifyKeyspaceEvent(NOTIFY_GENERIC,"del",targetkey,c->db->id);
-    }
         server.dirty++;
+    }
     addReplyLongLong(c,maxlen); /* Return the output string length in bytes. */
 }