chromium: Fix updater to handle versions > 26.

Starting with version 26, there is a chromium-$version-lite package and it is an
LZMA archive as well, so download size is reduced by about 44%.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
chromium: Update stable channel to v24.0.1312.69.

Let's begin with the most trivial one: The stable version.
This version just contains a few bug fixes and builds fine so far.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
chromium: Update beta channel to v25.0.1364.68.

This update is a bit more problematic, as the bundled version of libpng is
version 1.2.45 and the version in nixpkgs is 1.5.13. Even if trying to run with
libpng12 from nixpkgs, it seems to collide with parts of the bundled version.

So, until this is either fixed upstream or we have a good solution, we're using
bundled libpng for chromium version 25 and higher.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
virtualbox: Fix unpacking of extension pack.

This fixes a typo introduced by 5a3f9c08b0e1e004606fe331bf34ad112c710bcd.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>