Added LLVM package
Partial commit of more packages.
Better C++11 support, remove non-standalone llvm-compiler-rt.

- LLVM non-standalone add-ons are difficult to build outside LLVM.
- May have to wait for future versions of LLVM to build some of these
Merge branch 'features/llvm' into develop

- merging parts of LLVM that can be built now.
- need to wait for standalone builds for some of the others.