* scripts/autotools-install (tarballs): Use http:// URLs rather
than ftp:// ones. The former are more likely to work, these days.
Update URLs to point to the latest versions.
* scripts/autotools-install: Honor $MAKE. This might be useful
on systems where the make implementation available in $PATH
by default is limited (Solaris) or broken (HP-UX).
* scripts/autotools-install: New script, so you can always build
from git-cloned sources, even when they require bleeding edge
m4, autoconf, automake, etc.
