configure: s/don't/do not/

The autoconf manual suggests not to use ' in messages.

I don't why they do, but it breaks syntax-highlighting.

Just remove the lone quote we have.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

# Compute sparc-specific values

CT_DoArchTupleValues() {

    # That's the only thing to override

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

        CT_TARGET_ARCH="sparc64${CT_ARCH_SUFFIX}"

    fi

}