scripts: unquoted variable reference in glibc-eglibc.sh-common

Signed-off-by: Daniel Price <daniel.price@gmail.com>
Message-Id: <12f092a95a94bcf76912.1353367250@redfish.dssd.com>
Patchwork-Id: 200215

 # Compute s390-specific values

 CT_DoArchTupleValues() {

     # That's the only thing to override

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

         CT_TARGET_ARCH="s390x"

     fi

 }