i#1686 arm decoder testing: OP_ldrd encoding chain fix
i#1686 arm decoder testing: OP_ldrd encoding chain fix

Fixes an encoding chain error for OP_ldrd due to
bbb071d6a18977f3b2360c27ebffb1a82bd08e39 failing to run the encoding chain
script.

Review-URL: https://codereview.appspot.com/229050044

bl4ckic3/dynamorio,code4bones/dynamorio,code4bones/dynamorio,bl4ckic3/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,daksunt/dynamorio,bl4ckic3/dynamorio,bl4ckic3/dynamorio,daksunt/dynamorio,daksunt/dynamorio,code4bones/dynamorio,daksunt/dynamorio,AmesianX/dynamorio,code4bones/dynamorio,code4bones/dynamorio,AmesianX/dynamorio,daksunt/dynamorio,bl4ckic3/dynamorio,AmesianX/dynamorio