cc/gcc: do not print multilib for canadian-cross

Previous import from patchwork missed one hunk (in cset #d8feb93b3e49)
Apply it now.

Signed-off-by: "David Holsgrove" <david.holsgrove@xilinx.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Patchwork-Id: 189053

 # Compute s390-specific values

 CT_DoArchTupleValues() {

     # That's the only thing to override

     if [ "${CT_ARCH_64}" = "y" ]; then

         CT_TARGET_ARCH="s390x"

     fi

 }