the libtoolX ports instead of the one included with each port.  Ports that
set USE_LIBTOOL_VER=X will now use the ports version of libtool instead of
the included version.  To restore previous behavior, use the new macro,
USE_INC_LIBTOOL_VER.  Both macros accept the same argument: a libtool version.

For example, to use the ports version of libtool-1.5, add the following to
your Makefile:

USE_LIBTOOL_VER=        15

To use the included version of libtool with extra hacks provided by
libtool-1.5, add the following to your Makefile:

USE_INC_LIBTOOL_VER=    15

With this change, ports that had to add additional libtool hacks to prevent
.la files from being installed or to fix certain threading issues can now
delete those hacks (after appropriate testing, of course).

PR:		63944
Based on work by:eik and marcus
Approved by:	ade (autotools maintainer)
Tested by:	kris on pointyhat
Bound to be hidden problems:	You bet