Backport of "gst_writev: respect IOV_MAX for the writev iovec array #439" into 1.16
Backport of !277 (merged) "gst_writev: respect IOV_MAX for the writev iovec array #439 (closed)".
Commits:
- dc5250e7 gst_writev: respect IOV_MAX for the writev iovec array #439 (closed)
- a4aa2256 consolidated IOV_MAX/UIO_MAXIOV handling per GLib + legacy behaviour for osx/ios