osg3: Fix building on OSX 10.8

We can't use our own compilers. We must use Apple's for their block
extension, which their headers for Cocoa use heavily. Such is life.
osg3: packages: Deep copy env for each package

If a package like OSG changes the compiler. We don't want to change
the compiler for all packages. So we need to deep copy env.
osg3: Reenable inventor drivers, fixes point2mesh
Turn on make check for VW