Implemented ConstantPointerNull for integer operands.
Implemented ConstantPointerNull for integer operands.

surround-io/oclgrind,surround-io/oclgrind,bitfusionio/Oclgrind,mpflanzer/Oclgrind,mpflanzer/Oclgrind,surround-io/oclgrind,bitfusionio/Oclgrind,mpflanzer/Oclgrind,surround-io/oclgrind,bitfusionio/Oclgrind,mpflanzer/Oclgrind,bitfusionio/Oclgrind