- After finishing the first buildloop we have to go back to
  toplevel srcdir
- This commit also changes the priority of the preconf hook we
  use while building multilib.

  Warning:
  The change of the priority is very sensitive, so you should
  just change it if you really know what you are doing!

Note:
From now on we do not rely on the glibc32 package anymore by using a second
buildloop while building a 64bit multilib target.