message: add option for USER_SPACE
diff: @@ -120,6 +120,9 @@ endif
  ifeq (${BUILD_PYTHON}, 1)
  EXTENSIONS:=${EXTENSIONS} -DBUILD_PYTHON=1 -DBUILD_JSON_EXTENSION=1 -DBUILD_FTS_EXTENSION=1 -DBUILD_TPCH_EXTENSION=1 -DBUILD_VISUALIZER_EXTENSION=1 -DBUILD_TPCDS_EXTENSION=1
  endif
  +ifeq (${PYTHON_USER_SPACE}, 1)
  + EXTENSIONS:=${EXTENSIONS} -DUSER_SPACE=1
  +endif
  ifeq (${BUILD_R}, 1)
  EXTENSIONS:=${EXTENSIONS} -DBUILD_R=1
  endif
  