gstlibav: fix build with wrapped FFmpeg
The FFmpeg wrapped version was inferior to 60.31.100 and so it was forcing gstlibav to use the reordered_opaque
field causing a build error for using a deprecated field.
The FFmpeg wrapped version was inferior to 60.31.100 and so it was forcing gstlibav to use the reordered_opaque
field causing a build error for using a deprecated field.