Simplify the mirror settings.

-------- diffstat follows --------
/trunk/scripts/functions | 7 3 4 0 ++---
/trunk/config/global/download.in | 60 14 46 0 +++++++++++-----------------------------------
2 files changed, 17 insertions(+), 50 deletions(-)

 # Compute x86_64-specific values

 CT_DoArchTupleValues() {

     # The architecture part of the tuple:

     CT_TARGET_ARCH="${CT_ARCH}"

 }