Add line between licenses in COPYING.

More clearly delineate which files are associated with each license.
12 jobs for line_between_licenses in 18 minutes and 40 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Build
passed #6024930
gst-macos-10.15
meson macos

00:05:50

passed #6024927
meson-mingw-w64-build

00:05:42

manual #6024931
docker windows 1809 allowed to fail manual
meson msys2
passed #6029278
meson-shared-build

00:04:42

passed #6025464
meson-static-build

00:04:33

passed #6024928
docker windows 1809
meson vs2017 amd64

00:01:43

passed #6024929
docker windows 1809
meson vs2017 x86

00:01:44

passed #6024924
mingw-build

00:06:21

passed #6024922
shared-build

00:07:42

passed #6024923
static-build

00:05:56

failed #6024925
meson-shared-build

00:05:48

failed #6024926
meson-static-build

00:05:23