message: explicitly specify OSPCOMMON_TBB_ROOT, env variables don't work here
diff: @@ -111,6 +111,7 @@ if (NOT BUILD_DEPENDENCIES_ONLY)
  -Dembree_DIR:PATH=${EMBREE_PATH}
  -Dospcommon_DIR:PATH=${OSPCOMMON_PATH}
  -DISPC_EXECUTABLE=${ISPC_PATH}
  + -DOSPCOMMON_TBB_ROOT=${TBB_PATH} # NOTE(jda)- can't use env var here
  BUILD_COMMAND ${DEFAULT_BUILD_COMMAND}
  BUILD_ALWAYS OFF
  )
  