[OpenSCAD] compiling with clang

[Don Bright]

Got a compile with the Clang compiler working on ubuntu 12. There is a
new branch of the OpenSCAD that may make this a bit easier..

git clone git://github.com/openscad/openscad.git
cd openscad
git checkout clang
source ./scripts/setenv-linbuild-clang.sh
./scripts/linux-build-dependencies.sh
qmake && make

This will attempt to download and compile a bunch of the dependencies
using clang itself into $HOME/openscad_deps, including the recently
released CGAL 4.0.2 which is required to build with clang.

Test results are here and look pretty good:

http://cakebaby.wikia.com/wiki/OpenSCAD_linux_i686_mesa-dri-intel%28r%29_wwbg_test_report

I think a main problem is that I don't know how to download MCAD and
stick it into the proper place?

Interesting note is that clang requires much less memory than gcc on a
non-debug build, maybe 40-50 percent less.

-DB