in some edge cases we want to install binaries into paths
other than ${PREFIX}/bin and shared files in paths other
than ${PREFIX}/usr/share. This commit allows doing that
by including GNUInstallDirs for Linux builds, which allows
passing `CMAKE_INSTALL_DATAROOTDIR` and `CMAKE_INSTALL_BINDIR`
to cmake to customise these paths. If these aren't supplied
nothing changes, their defaults values equal to `bin` and `shared`,
as before.
The desktop files (entries) are required to launch plexmediaplayer
via a GUI (instead of launching it via a terminal), the accompanying
icon is required so that the desktop entry has an icon.
Until now distros had to carry downstream patches to install
desktop files and plex's icons, with this commit we install
our own files.
Plex-CLA-1.0-signed-off-by: Rasmus Thomsen <cogitri@exherbo.org>