This give us a little bit more control over what target we are using.
Eventually we can target other things like WatchOS or MacOS.

perl-packages.nix: duplicate packages -> aliases

mark old and unmaintained by upstream packages as broken

By convention, git-related tools in nixpkgs are not added to
the top level but bundled under gitAndTools.

Add git sync

lief: init at 0.9.0

qiskit: fix build

 ocamlPackages.re: 1.7.1 -> 1.7.3

xcode: add xcodePlatform to system

ocamlPackages.psmt2-frontend: init at 0.1

`minitube` is currently broken transitively due to the broken
`phonon-backend-qt4`: https://hydra.nixos.org/build/76523277

Although QT4 is fairly old, this package is still built with `qt4` ATM,
however QT5 is available as well. After this change, QT5 will be built
by default and in case anybody requires legacy QT4 it has to be enabled
explicitly like this:

```
with import <nixpkgs> { };
phonon-backend-vlc.override { withQt4 = true; }
```

Now the QT5-only build can be used (which fixes `minitube`) and there
are no confusions anymore with the build dependencies. Previously
`phonon-backend-vlc` and `libsForQt5.phonon-backend-vlc` used `qt4` by
default which was likely responsible for broken `minitube`.

During `8d6502f8ca9` `phonon-backend-vlc` uses QT5 by default.
Rather than fixing this it has been marked as broken as it's currently
unmaintained (see c76ad47)
and broken since March (https://hydra.nixos.org/build/71873808).
For now I've marked it as broken as the last *stable* release is from
2015 (see https://github.com/tomahawk-player/tomahawk/releases/tag/0.8.4).

phonon-backend-vlc: use qt5 by default