Moved the PXC-dealing parts of Cxn.pm into Percona::XtraDB::Cluster

t/pt-table-checksum/pxc.t

@@ -21,12 +21,10 @@ $ENV{PERCONA_TOOLKIT_TEST_USE_DSN_NAMES} = 1;
 
 use PerconaTest;
 use Sandbox;
-use VersionParser;
 
-# Fix @INC because pt-table-checksum uses subclass OobNibbleIterator.
-shift @INC;  # our unshift (above)
-shift @INC;  # PerconaTest's unshift
 require "$trunk/bin/pt-table-checksum";
+# Do this after requiring ptc, since it uses Mo
+require VersionParser;
 
 my $dp = new DSNParser(opts=>$dsn_opts);
 my $sb = new Sandbox(basedir => '/tmp', DSNParser => $dp);