debug/gdb: update the version strings

Almost all versions have been renamed, but the gdb folks did not
setup legacy symlinks.

For more information, see this message:
http://sourceware.org/ml/gdb/2011-09/msg00002.html

Reported-by: ManuelStahl <manuel.stahl@iis.fraunhofer.de>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# Compute s390-specific values

CT_DoArchTupleValues() {

    # That's the only thing to override

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

        CT_TARGET_ARCH="s390x"

    fi

}