Fix a bug with OS_ConvertInteger4 in arm_vm
Fix a bug with OS_ConvertInteger4 in arm_vm

The code was copying the NULL pointer into the buffer.  This seems
to be because the printi implementation used write0.  Since printi
is now gone we can fix this.

Signed-off-by: Mark Ryan <88ffc4093c40652fbbf052f026a8b6147509f0aa@gmail.com>

markdryan/subtilis,markdryan/subtilis