Correction to costing rect_tx

When built with var_tx and ext_tx, select_tx_size_fix_type is used
to compute the cost for using a particular tx_type.
The code indexes the array inter_tx_type_costs at the wrong location
resulting in a zero cost for signalling tx_type for rect_tx blocks.

Change-Id: Iba38be3a0d822109f778f0600b242dfb40359766
1 file changed