ptxed: support empty blocks
ptxed: support empty blocks

For empty blocks, ptxed's print_block() would try to decode UINT32_MAX
instructions in sequence.  Add a block->ninsn == 0 check to avoid the
wrap-around.

Change-Id: Iccff86ce34262e90461cbd9a2994e6209f21df58
Signed-off-by: Markus Metzger <5f675b2b36595f90898e014b548ff7d9bbff2ab7@intel.com>

01org/processor-trace,01org/processor-trace,01org/processor-trace