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]
The affected ports are the ones with gettext as a run-dependency
according to ports/INDEX-7 (5007 of them) and the ones with USE_GETTEXT
in Makefile (29 of them).
PR: ports/124340
Submitted by: edwin@
Approved by: portmgr (pav)
