COPYING.LGPL: add LGPL license text

Some bits (shared/ in particular) are LGPL licensed.
6 jobs for lr/copying-lgpl in 14 minutes and 16 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Build
passed #494394
fedora28_dist

00:08:03

 
  Test
passed #494399
centos7

00:03:14

passed #494398
fedora_autotools_full

00:06:13

failed #494397
fedora_autotools_minimal

00:00:21

passed #494396
fedora_meson_full

00:02:23

passed #494395
fedora_meson_minimal

00:04:54

 
Name Stage Failure
failed
fedora_autotools_minimal Test
Skipping Git submodules setup
Downloading artifacts for fedora28_dist (494394)...
Downloading artifacts from coordinator... ok id=494394 responseStatus=200 OK token=zc_DBTQ9
$ dnf -y install file findutils gcc desktop-file-utils gettext-devel glib2-devel gtk3-devel NetworkManager-libnm-devel pkgconfig /usr/bin/autopoint
Fedora Modular 31 - x86_64 3.2 MB/s | 5.2 MB 00:01
Fedora Modular 31 - x86_64 - Updates 1.0 MB/s | 1.0 MB 00:01
Failed to download metadata for repo 'updates-modular'
Error: Failed to download metadata for repo 'updates-modular'
ERROR: Job failed: exit code 1