devel/subversion: Add Differential Revision: to FreeBSD template

Given that it has been possible for a while to close Phabric's Differential
Revisions through svn commits, amend the subversion template to match this
behavior.

Differential Revision:  https://reviews.freebsd.org/D600
Approved by:		koobs (mentor)
Approved by:		portmgr (mat)


git-svn-id: svn+ssh://svn.freebsd.org/ports/head@367920 35697150-7ecd-e111-bb59-0022644237b5
- Update to 2.18
  Change:
  * Adapt to ocaml 4.02, use 'Bytes' module + backward compatibility hack.
  * Some patches by Damien: typos + illegal format strings.


git-svn-id: svn+ssh://svn.freebsd.org/ports/head@367921 35697150-7ecd-e111-bb59-0022644237b5
Add USES=libtool


git-svn-id: svn+ssh://svn.freebsd.org/ports/head@367922 35697150-7ecd-e111-bb59-0022644237b5