Resolves issue on OS X Lion where Macvim starts up but unable to windows

I believe this issue is the same issue and/or strongly related to https://github.com/alloy/macvim/issues/68. Explanation for this is likely related to the special "notes" under the build instructions for the upstream macvim repo. See https://github.com/b4winckler/macvim/wiki/Building#how-to-build-macvim

**Not sure if this breaks a build on OS X Mountain Lion. Will test that shortly**