Export symbol gpuSetPeriodicBoxSize for Cuda FreeEnergy plugin on windows.

Turn default to ON for nightly building Cuda FreeEnergy plugin, since it is desired for pyopenmm release.

platforms/cuda/src/kernels/gputypes.h

@@ -243,7 +243,7 @@ extern "C"
 void gpuSetPMEParameters(gpuContext gpu, float alpha, int gridSizeX, int gridSizeY, int gridSizeZ);
 
 extern "C"
-void gpuSetPeriodicBoxSize(gpuContext gpu, float xsize, float ysize, float zsize);
+void OPENMMCUDA_EXPORT gpuSetPeriodicBoxSize(gpuContext gpu, float xsize, float ysize, float zsize);
 
 extern "C"
 void gpuSetObcParameters(gpuContext gpu, float innerDielectric, float solventDielectric, const std::vector<float>& radius, const std::vector<float>& scale, const std::vector<float>& charge);

plugins/freeEnergy/CMakeLists.txt

@@ -154,7 +154,7 @@ ADD_SUBDIRECTORY(platforms/reference/tests)
 
 # Which hardware platforms to build
 
-SET(OPENMM_BUILD_FREE_ENERGY_CUDA_LIB OFF CACHE BOOL "Build OpenMMFreeEnergyCuda library for Nvidia GPUs")
+SET(OPENMM_BUILD_FREE_ENERGY_CUDA_LIB ON CACHE BOOL "Build OpenMMFreeEnergyCuda library for Nvidia GPUs")
 
 SET(OPENMM_BUILD_FREE_ENERGY_PATH)
 SET(OPENMM_BUILD_FREE_ENERGY_CUDA_PATH)