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.
The behavior has been like that since forever, but this specific nonbonded flavor looks too exotic to be worth backporting to 2020, IMHO.
Closes #3840 (closed)
Edited by Andrey Alekseenko