[Beignet] opencv_test_imgproc crashs when test OCL_Imgproc/HoughLines.RealImage/0

[yan.wang at linux.intel.com]

Hi, All,
  This case will crash as the following:
  [ RUN      ] OCL_Imgproc/HoughLines.RealImage/0
ASSERTION FAILED: defIt != bbIt->second->end() && defIt->second != NULL
  at file /home/yanwang/beignet/backend/src/ir/value.cpp, function
gbe::ir::LiveOutSet::RegDefSet& gbe::ir::LiveOutSet::getDefSet(const
gbe::ir::BasicBlock*, gbe::ir::Register), line 91
  Thanks.

Yan Wang