Use simpler wrap logic to maximize range

lib/memjs/memjs.js

@@ -798,13 +798,12 @@ Client.prototype.perform = function(key, request, seq, callback, retries) {
 
 // Increment the seq value
 Client.prototype.incrSeq = function() {
-  // Prevent seq from being larger than 2^31
-  // so that range errors do not occur. In event
-  // this occurs we simply roll over the value.
-  if (this.seq >  Math.pow(2,31)) {
+  // Wrap `this.seq` to 32-bits since the field we fit it into is only 32-bits.
+  if (this.seq == 0xffffffff) {
     this.seq = 0;
+  } else {
+    this.seq++;
   }
-  this.seq++;
 };
 
 exports.Client = Client;