ports/76941: Patch to science/vmd: compile and run vmd on amd64 machine.

[Sangwoo Shim]

I forgot to add PLIST_SUB. Updated patch and port tarball are:
http://www.swoo.org/~sangwoo/vmd-amd64-2.diff
http://www.swoo.org/~sangwoo/vmd-amd64-2.tar.bz2

- Sangwoo Shim