Bug 54412

    When using USE_LIBTOOL_VER in a ports Makefile, various environment variables
    are extended with the supplied path to the libtool executables.
    The same is done when having USE_AUTOMAKE_VER or USE_AUTOCONF_VER, so e.g. 
    SCRIPTS_ENV ends up like this:

    PORTOBJFORMAT=elf PATH=/usr/local/libexec/autoconf213:/sbin:/bin:/usr/sbin:/usr/bin:/usr/games:/usr/local/bin:/usr/local/sbin:/usr/X11R6/bin:/root/bin PATH=/usr/local/libexec/libtool13:/sbin:/bin:/usr/sbin:/usr/bin:/usr/games:/usr/local/bin:/usr/local/sbin:/usr/X11R6/bin:/root/bin BSD_INSTALL_PROGRAM=install -c -s -o root -g wheel -m 555 BSD_INSTALL_SCRIPT=install -c -o root -g wheel -m 555 BSD_INSTALL_DATA=install -c -o root -g wheel -m 444 BSD_INSTALL_MAN=install -c -o root -g wheel -m 444 CURDIR=/mnt/home/alex/libtoolbug DISTDIR=/usr/ports/distfiles WRKDIR=/mnt/home/alex/libtoolbug/work WRKSRC=/mnt/home/alex/libtoolbug/work/php-gtk-0.5.2 PATCHDIR=/mnt/home/alex/libtoolbug/files SCRIPTDIR=/mnt/home/alex/libtoolbug/scripts FILESDIR=/mnt/home/alex/libtoolbug/files PORTSDIR=/usr/ports DEPENDS= PREFIX=/usr/local LOCALBASE=/usr/local X11BASE=/usr/X11R6

    The PATH= setting shows up twice with the last entry overwriting the first one. As a consequence,
    either libtool is in the current path or autoconf/automake, whichever is in the 'last'
    PATH.

    This breaks e.g. PHP's phpize.

How-To-Repeat:     Use a Makefile like this (showing only the essential lines):

    USE_LIBTOOL_VER=    14
    USE_AUTOMAKE_VER=   15
    USE_AUTOCONF_VER=   253

    pre-configure:
        @${ECHO_MSG} ${SCRIPTS_ENV}