chromium: Update all channels to latest versions.

With this commit, the following new upstream versions are introduced:

stable: 36.0.1985.125 -> 37.0.2062.94
beta:   37.0.2062.58  -> 37.0.2062.94
dev:    38.0.2107.3   -> 38.0.2125.8

All channels built fine on my machine and were tested.

Stable and beta channel now contain the same release, because version
37 hit the stable channel. For release notes, please have a look at the
announcement:

http://googlechromereleases.blogspot.de/2014/08/stable-channel-update_26.html

Of course we're also dropping all version 36 specific crap, such as the
architecture-specific target suffix for builds, which now is no longer
needed.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
squash! chromium: Update all channels to latest versions.

Drop obsolete workaround use_mojo = false... XXX: search for the reason
it's not needed anymore.