binutils/binutils: fix extra config array variable name

The changeset 2467 #200836977ce6 missed renaming one occurrence of
CT_BINUTILS_EXTRA_CONFIG to CT_BINUTILS_EXTRA_CONFIG_ARRAY, which is fixed by
this patch.

Signed-off-by: "Benoît Thébaudeau" <benoit.thebaudeau@advansee.com>
(transplanted from 8946dd980d9e6c3da3b8f63fe7e35f4af94acf2f)

# Compute s390-specific values

CT_DoArchTupleValues() {

    # That's the only thing to override

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

        CT_TARGET_ARCH="s390x"

    fi

}