Add 4 to the number of bytecodes.

The NWords variable counts the nunber of words with
instructions after the current word. The
continue_unwind method calls _Unwind_VRS_Interpret
with this same number, which VRS_Interpret
takes literally. But this means it loses the
last 4 instructions (or 3 if there's only 1 word).

Change-Id: I80032cb9cc570ea8ea05542a5b3973ac1abb2cf5