Checking in changes prior to tagging of version 0.22.

Changelog diff is:

diff --git a/perl/Changes b/perl/Changes
index 5d5a5e2..dd47b98 100644
--- a/perl/Changes
+++ b/perl/Changes
@@ -1,3 +1,7 @@
+0.22
+
+    - fixed issue on ithreads(broken from 0.21)
+
 0.21

     - doc enhancment

perl/Changes

@@ -1,3 +1,7 @@
+0.22
+
+    - fixed issue on ithreads(broken from 0.21)
+
 0.21
 
     - doc enhancment

perl/MANIFEST.SKIP

@@ -25,3 +25,4 @@
 ^Data-MessagePack-[0-9.]+/
 ^\.testenv/test_pp.pl
 ^ppport.h$
+^xshelper.h$

perl/lib/Data/MessagePack.pm

@@ -3,7 +3,7 @@ use strict;
 use warnings;
 use 5.008001;
 
-our $VERSION = '0.21';
+our $VERSION = '0.22';
 our $PreferInteger = 0;
 
 our $true  = do { bless \(my $dummy = 1), "Data::MessagePack::Boolean" };