* Use gcc and g++ rather than cc and c++, as the latter now point to
clang with recent Xcode versions and compilation of the host tools
fail for various reasons with it.
* Replace the case-sensitive filesystem check with a more basic one,
as diskutil no longer supports the behaviour of getting info for the
volume that any path is on.
* Updated ReadMe with a correct list of prerequisites for OS X.
* GCC 2 builds are still broken due to a strange error that only
occurs with a GCC 2 built on OS X 10.7
Alex Smith
0962132cc6