Comment 3 for bug 1668024

Debian beignet automatically uses the same LLVM version as mesa, to avoid crashing when OpenCL and OpenGL are used together (as LLVM lacks symbol versioning - https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=848368#46 ). Ubuntu -proposed mesa now uses LLVM 4.0, which beignet isn't compatible with (adding the dependency only makes it fail later), so this no longer works.

The immediate fix is to disable this mechanism and use LLVM 3.9, as attached. (This will have the above bug if LLVM 4.0 mesa is let out of -proposed, but so would the existing beignet, built with 3.9 before mesa switched.)