PFCOUNT: always unshare/decode the object.

This will be a non-op most of the times since the object will be
unshared / decoded, however it is more technically correct to start this
way since the object may be decoded even in the read-only code path.

src/hyperloglog.c

@@ -520,6 +520,7 @@ void pfcountCommand(redisClient *c) {
         addReply(c,shared.czero);
     } else {
         if (isHLLObjectOrReply(c,o) != REDIS_OK) return;
+        o = dbUnshareStringValue(c->db,c->argv[1],o);
 
         /* Check if the cached cardinality is valid. */
         registers = o->ptr;
@@ -535,9 +536,6 @@ void pfcountCommand(redisClient *c) {
             card |= (uint64_t)registers[REDIS_HLL_SIZE-9] << 56;
         } else {
             /* Recompute it and update the cached value. */
-            o = dbUnshareStringValue(c->db,c->argv[1],o);
-            registers = o->ptr;
-
             card = hllCount(registers);
             registers[REDIS_HLL_SIZE-16] = card & 0xff;
             registers[REDIS_HLL_SIZE-15] = (card >> 8) & 0xff;