Fix defining of EXCLUSION_FORCES in CUDA/OpenCL kernels

Fix defining of EXCLUSION_FORCES in CUDA/OpenCL kernels

For the case of cut-off electrostatics + Ewald LJ + no energy calculation,
the EXCLUSION_FORCES macro should be active.
However, LJ_EWALD macro is (conditionally) set only later, and so is
always undefined when it is being checked for EXCLUSION_FORCES.