ports/69695: update: net/unison to link under ocaml 3.08

[Dan Pelleg]

The proposed patch, however simple, breaks compilation under ocaml 3.07.

The unison team is not likely to produce patches that work for both 3.07
and 3.08 [1].

At this point, the options as I see them are:

1. Patch unison so it builds for both versions. See [2].

2. Add logic to the port so it can patch conditionally, depending on the
installed version of ocaml.

3. Forget about support for 3.07. This will break systems that had
installed ocaml previously, and now want to install unison.

To me it seems option (2) is best, and is likely to benefit other ports as
well. This has been done for mldonkey in ports/61012. But if there is a more
general approach (unison has no configure script), it sure would be nice to
just branch on version of the installed ocaml.



[1] http://groups.yahoo.com/group/unison-users/message/2649
[2] http://article.gmane.org/gmane.comp.lang.ocaml.lib.devel/1122