Pidgin 2.10.9 has landed into wheezy-security, while wheezy-backports is now
lagging behind.

Note that:

* linux-compiler-gcc-4.8-x86 is needed to install linux-headers-3.12-*
* linux-kbuild-3.12 is only available from sid right now

It has been maintained there for a while, and in the feature/wheezy branch we
have no good reason to go on using the older Squeeze version we have in our
APT repository.

Install libnss3, libnss3-1d, libnspr4, libnspr4-0d, libsqlite3-0 and sqlite3 from the official squeeze-backports.

This addresses #6496, assuming Iceweasel 24.2.0esr-1+tails1~bpo60+1 is happy
enough with these versions. Then, we can remove these packages from our own
APT repository.

It is needed to install linux-headers-3.12-trunk-486.

This reverts commit 05dcca3d.

This reverts commits 945796fe
and 6bebc91c.

The APT pinning for linux*3.10* is actually useless, as these packages are not
in Debian testing anymore and will be covered by the general pinning rules that
apply to our own APT repository. Let's keep these lines around so that we don't
forget to adapt them once we move forward to a newer kernel again.

Otherwise, ISO builds fails since a hook of ours tries to get the former in its
newest version (from mozilla.d.n) and we have pinning that gets the later from
official backports, which are not compatible with each other.

It's needed by the latest tails-perl5lib.

We've uploaded the version we want there, no need to fetch the package from
sid anymore.

The version needed by FF24 is now in there.

It was updated to a good enough version in there as part of a Wheezy
point-release, no need to track unstable.

The version in there is good enough for the version of Iceweasel we
currently ship. Besides, it's the same as in sid as of today.

So, no need to track unstable on that one.

On Wheezy, we don't need anything more recent than the stable versions,
so better stick to them.

This version is enough for current sid's kernel, no need to fetch it from sid.

Now that we have the appropriate configuration to make good use of it,
here we go.

Besides, it's now required by intel-microcode, so we cannot skip it anymore.

On Wheezy, we cannot rely on "origin backports.debian.org" anymore,
as the backports were merged into the regular archive.

A new kernel (3.11.5-1) entered Debian unstable, and we don't want to ship
a different kernel in 0.21 final than what we had in 0.21~rc1 (3.10.11-1).

Actually, the hide_on_start setting was simply migrated to dconf, under
a different name.

Some (backported) dependencies of Iceweasel 24 are only available in there.
Also, stop pinning some of these dependencies to backports.d.o, since the
version we need is only at mozilla.d.n.

This will have to be changed to their iceweasel-esr repository once FF24 is the
new ESR.

This reverts commit 06d053c8.

The backport has its own share of issues, such as Debian#628124.