Enable compilation of the NVIDIA OpenCL demos under Linux,

Thanks to Xavier Thomas, see Issue 417

Demos/ParticlesOpenCL/NVidia/CMakeLists.txt

@@ -29,6 +29,9 @@ ELSE(CMAKE_CL_64)
 	SET(CMAK_GLEW_LIBRARY		${BULLET_PHYSICS_SOURCE_DIR}/Glut/glew32.lib		)
 ENDIF(CMAKE_CL_64)
 
+IF(UNIX AND NOT APPLE)
+	SET(CMAK_GLEW_LIBRARY		/usr/lib/libGLEW.so		)
+ENDIF()
 
 IF (USE_GLUT)
 	LINK_LIBRARIES(
@@ -40,10 +43,9 @@ IF (USE_GLUT)
 		${OPENGL_gl_LIBRARY} 
 		${OPENGL_glu_LIBRARY}
 		${CMAK_GLEW_LIBRARY}
-		${CMAK_NVSDKCOMPUTE_LIBPATH}/OpenCL.lib
+		${NVIDIA_OPENCL_LIBRARIES}
 	)
 
-
 	ADD_EXECUTABLE(AppParticlesOCL_Nv
 					${BULLET_PHYSICS_SOURCE_DIR}/Demos/ParticlesOpenCL/btParticlesDynamicsWorld.h
 					${BULLET_PHYSICS_SOURCE_DIR}/Demos/ParticlesOpenCL/btParticlesSharedDefs.h