doc/macports.conf.in: add -l option to rsync_options.
doc/macports.conf.in: add -l option to rsync_options.

For plain rsync-updating of base, not handling symlinks will skip them
and thus lead to compile errors when building base's internal TCL
version - which is symlinked to vendor/tcl.

This is not needed for the new and preferred tarball mechanism.

macports/macports-base,neverpanic/macports-base,danchr/macports-base,danchr/macports-base,macports/macports-base,neverpanic/macports-base