ges/ges-track-transition.c: set referece to vsmpte to NULL after freeing
ges/ges-track-transition.c: set referece to vsmpte to NULL after freeing

volodymyrrudyi/gst-editing-services,pitivi/gst-editing-services,cfoch/gst-editing-services,freesteph/gst-editing-services,freesteph/gst-editing-services,cfoch/gst-editing-services,cfoch/gst-editing-services,cfoch/ges,pitivi/gst-editing-services,ahmedammar/platform_external_gst_editing_services,luisbg/gst-editing-services,MathieuDuponchelle/PitiviGes,cfoch/ges,freesteph/gst-editing-services,ahmedammar/platform_external_gst_editing_services,volodymyrrudyi/gst-editing-services,luisbg/gst-editing-services,MathieuDuponchelle/PitiviGes,cfoch/ges,pitivi/gst-editing-services,cfoch/ges,volodymyrrudyi/gst-editing-services,MathieuDuponchelle/PitiviGes,cfoch/gst-editing-services,MathieuDuponchelle/PitiviGes,pitivi/gst-editing-services