vim: convert to autotargets, bump to version 7.2.446

* Convert to autotargets package.
* Bump to version 7.2.446.

We fetch from svn to avoid having a ton of patch files.

This won't do us any good if we want vim 7.3 since the repository was
moved to mercurial. However 7.3 still has some cross-compile issues.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>