`glvideoflip` `method` property is broken if set during element construction

Both the method and video-direction properties are marked as G_PARAM_CONSTRUCT, which means GLib will always set a value for them during construction - either the value provided to g_object_new_with_properties(), or the default if not provided.

In practice, that means that gst-launch-1.0 videotestsrc ! glupload ! glvideoflip method=rotate-180 ! glimagesink is broken, because GLib will first set method to 180°, and then set video-direction to the default (0). Since both properties do the same thing, the 2nd set_property always overrides the first.

Removing the G_PARAM_CONSTRUCT flag means the method property doesn't get set until after construction and things work.

Is there any reason for the properties to be G_PARAM_CONSTRUCT? Any reason not to remove the flag from both?