Use BinaryProvider for All OSes

[programmeroftheeve]

This would take a lot of the guess work out of making sure that LLVM is installed. It would also allow the libclang used to match julia's LLVM.

[ihnorton]

Yes. See comments on #210
I believe we are waiting for an upstream fix.

[Gnimuc]

hi, @btaidm, I just released Julia 1.0-compatible libclang binaries, you could give it a try now:

add Clang#6b1bb2b53becb1bba615315172ab8e1ff16dada3