absolute-symlink.sh: check for absolute symlinks on a FreeBSD system

The purpose of this script is to detect absolute symlinks on
a machine, e.g.:

/etc/localtime -> /usr/share/zoneinfo/UTC

Some of these absolute symbolic links can be created intentionally,
but it is usually better to use relative symlinks.

You can run the script after `make installworld', or any other
make targets thats installs files.

You can also check your local ports with:

env ABSOLUTE_SYMLINK_DIRS=/usr/local ./absolute-symlink.sh