libigdfscl.so can crash on failure to load libcommon_clang.so

[dvrogozh]

intel-graphics-compiler/IGC/OCLFE/igd_fcl_mcl/source/clang_tb.cpp

Line 663 in 4be564f

dlclose(pTranslationBlock->m_CCModule.pModule);

libigdfscl.so can crash on failure to load libcommon_clang.so, for example this happens in the scenario described here: intel/opencl-clang#44. You may wish to consider:

1. Improve robustness by direct fix (check for nullptr before calling dlclose())
2. Refactor the code as described here: question: will it make sense to link against common_clang rather than load it? #71