How to enforce the use of libjava/scripts/jar?

[Gerald Pfeifer <gerald at pfeifer dot com>]

Looking at libjava/configure.ac, I understand that we only use and 
install libjava/scripts/jar.in if no version of jar nor fastjar is
already present in $PATH:

   AC_CHECK_PROGS([JAR], [jar fastjar], no)
   AC_PATH_PROG([ZIP], [zip], no)
   AC_PATH_PROG([UNZIP], [unzip], unzip)
   AM_CONDITIONAL(BASH_JAR, test "$JAR" = no)
   if test "$ZIP" = no; then
     if test "$JAR" = no; then
       AC_MSG_ERROR([cannot find neither zip nor jar, cannot continue])
     fi
   else
     # InfoZIP available, use the 'guaranteed' Bourne-shell JAR to build libjava
     JAR=`pwd`/scripts/jar
   fi

Now there are some cases where I would like us to always use scripts/jar,
regardless of what is already installed.

The FreeBSD Ports Collection is such an example, where a user may, or
may not, have jar or fastjar in his path, and the result of the build 
ill become less deterministic, especially wrt. the package list.

Also, if the user at one point "looses" jar or fastjar from her path, 
which may have come from a non-RPM or non-package, GCC will partly stop 
working because we relied on that instead of using and installing our
own copy, but the package database could not model this properly.

My question now is: Is there any way to enforce the use and installation
of our own copy of ${PREFIX}/bin/jar${PROGRAMSUFFIX}?

And if there is none, could we add one?

Gerald