Typo in build helpers: `MAXOSX_DEPLOYEMENT_TARGET`
build-helpers/i686-apple-darwin11-g++ and build-helpers/i686-apple-darwin11-gcc have a typo:
```
-DMAXOSX_DEPLOYEMENT_TARGET=10.6
```
There are actually two bugs: `MAXOSX` not `MACOSX` and `DEPLOYEMENT` not `DEPLOYMENT`.
Since this define has probably never had an effect, I suppose it can be removed.
issue