The element should allocate GstFdMemory large enough to fit incoming
memory's size plus its potential offset.
Fixes "gst_memory_resize: assertion 'size + mem->offset + offset <=
mem->maxsize' failed".
Fixes an issue reproducible on Raspberry Pi 4 that results in a garbled
image on the receiver's end:
gst-launch-1.0 libcamerasrc ! unixfdsink socket-path=/tmp/socket
gst-launch-1.0 unixfdsrc socket-path=/tmp/socket ! autovideosink
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8025>
75517d0faf