only install onelab.py if ENABLE_ONELAB is set

CMakeLists.txt

@@ -1462,7 +1462,9 @@ if(ENABLE_BUILD_SHARED OR ENABLE_BUILD_DYNAMIC)
   endif(WIN32 AND NOT MSVC OR CYGWIN)
 endif(ENABLE_BUILD_SHARED OR ENABLE_BUILD_DYNAMIC)
 
-install(FILES ${ONELAB_PY} DESTINATION ${GMSH_BIN})
+if(ENABLE_ONELAB)
+  install(FILES ${ONELAB_PY} DESTINATION ${GMSH_BIN})
+endif(ENABLE_ONELAB)
 if(ENABLE_BUILD_LIB OR ENABLE_BUILD_SHARED OR ENABLE_BUILD_DYNAMIC)
   install(FILES ${GMSH_API} DESTINATION include/gmsh)
 endif(ENABLE_BUILD_LIB OR ENABLE_BUILD_SHARED OR ENABLE_BUILD_DYNAMIC)