osxvideo: fix mac os 10.14 build (lockFocusIfCanDraw)

lockFocusIfCanDraw is deprecated in mac os 10.14.  Apple suggests a
different way to do what that does, but for now, just suppress the deprecation.

There's no way to disable just that deprecation, so shut them all down.

Did it in just osxvideo for automake, but couldn't figure out how to
do that for meson, so did it globally there.

gstreamer/gst-plugins-good#577
8 jobs for issue577-osx1014-deprecated-apis in 34 minutes and 7 seconds (queued for 1 minute and 15 seconds)
latest
Status Job ID Name Coverage
  Preparation
passed #179703
gst indent

00:00:57

passed #179702
manifest

00:00:47

 
  Build
passed #179704
build fedora x86_64

00:05:00

 
  Test
passed #179705
check fedora

00:04:31

 
  Full Builds
passed #179707
build cerbero android universal

00:22:46

passed #179708
build cerbero cross win32

00:10:42

passed #179709
build cerbero cross win64

00:07:50

passed #179706
build cerbero fedora x86_64

00:10:22