Fix constants in _kernel_constants.h
Fix constants in _kernel_constants.h

The filter/address mode/normalize constants cannot be tested using "==",
because all are in sampler_t; therefore they must be bit-testing macros.

Oblomov/pocl,rjodin/pocl,franz/pocl,Oblomov/pocl,rjodin/pocl,rjodin/pocl,franz/pocl,pocl/pocl,pocl/pocl,Oblomov/pocl,franz/pocl,franz/pocl,pocl/pocl,pocl/pocl,Oblomov/pocl,pocl/pocl,rjodin/pocl,Oblomov/pocl,franz/pocl