cutter: fix leak of unused GValue
cutter: fix leak of unused GValue

matsu/gst-plugins-good,freedesktop-unofficial-mirror/gstreamer-sdk__gst-plugins-good,matsu/gst-plugins-good,matsu/gst-plugins-good,freedesktop-unofficial-mirror/gstreamer-sdk__gst-plugins-good,freedesktop-unofficial-mirror/gstreamer-sdk__gst-plugins-good,freedesktop-unofficial-mirror/gstreamer-sdk__gst-plugins-good,matsu/gst-plugins-good