Fix build of gstreamer and gstreamer1 with glib 2.38.x [1].
Update gstreamer and gstreamer-plugins to new rules, USES=gmake pathfix,
new LIB_DEPENDS syntax.
Only pull in flex if base version is too old.
Be more selective for which OSVERSIONS we need gcc due to the clang bug.
Obtained from: Gstreamer upstream [1]
If a port used other USE_GNOME items it was untouched.
The ports that used other USES were fixed by hand.
PR: ports/177081
Reviewed by: bapt
Approved by: portmgr (miwi)
This Gstreamer plugin suppies:
* Integration with stanard GStreamer video buffers
* Various OpenGL effects and filters
* Direct GL output via glimagesink