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.
the USE_<x> equivalents. In the current scheme of things, the WANT_
variables in this case are synonymous with the USE_ ones, and thus need
to be exterminated.
First in a series of major autotools cleanups.
