debug/gdb: update Linaro GDB revisions to 2012.12-1

Update Linaro GDB with the latest available revisions.

Signed-off-by: "Benoît Thébaudeau" <benoit.thebaudeau@advansee.com>
Message-Id: <b6c4a82286f9a3de3948.1355761104@advdt005-ubuntu>
Patchwork-Id: 206907

# Compute s390-specific values

CT_DoArchTupleValues() {

    # That's the only thing to override

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

        CT_TARGET_ARCH="s390x"

    fi

}