Begin autotools sanitization sequence by requiring ports to explicitly
specify which version of {libtool,autoconf,automake} they need, erasing
the concept of a "system default".
For ports-in-waiting:
USE_LIBTOOL=YES -> USE_LIBTOOL_VER=13
USE_AUTOCONF=YES -> USE_AUTOCONF_VER=213
USE_AUTOMAKE=YES -> USE_AUTOMAKE_VER=14
Ports attempting to use the old style system after June 1st 2004 will be
sorely disappointed.
cyclic tasks. It will keep track of what you should have done, what you really
did, and is able to adjust each task's frequency until the optimal organization
is found.