Bug#717791: debian-installer: virtualbox guest additions not installed correctly

[Алексей Шилин <rootlexx@mail.ru>]

I confirm this.

Looks like the reason for having wrong kernel headers installed is the following dependencies chain:
  * virtualbox-ose-guest-x11 depends on virtualbox-guest-x11;
  * virtualbox-guest-x11 depends on virtualbox-guest-utils;
  * virtualbox-guest-utils recommends virtualbox-guest-dkms;
  * virtualbox-guest-dkms depends on dkms;
  * dkms recommends linux-headers-686-pae | linux-headers-amd64 | linux-headers-generic | linux-headers.

VirtualBox doesn't enable PAE/NX by default, so the installer chooses the 486 kernel for installation;
however, when requesting virtualbox-ose-guest-x11 installation, no kernel headers package is explicitly
requested by the installer, so APT chooses the default one, which is the first one in the dependencies list,
namely linux-headers-686-pae.

I guess, this can be fixed by explicitly requesting the kernel headers package, matching the kernel
installed.

-- 
Алексей Шилин