Recent devel/libclc update breaking graphics/dri - it seems

[Walter Schwarzenfeld]

Now it is the question, why it happens on your system. MAKE_LLVM_VER= 39 
is explicit set in the masterport (lib/libGL) and compiles with llvm39

without problems on my system (10.3amd64).

For the problem with llvm40 (I don't know if it is really relevant in 
the moment cause of MAKE_LLVM_VER) I opened a PR:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=218251