Enhance ./configure tools checking.
Add check for compatible autoconf.

/trunk/configure | 95 61 34 0 ++++++++++++++++++++++++++++++++++++++++----------------------
1 file changed, 61 insertions(+), 34 deletions(-)

# Compute x86_64-specific values

CT_DoArchValues() {

    # The architecture part of the tuple:

    CT_TARGET_ARCH="${CT_ARCH}"

}