bug#30282: package julia build error

[Pjotr Prins]

One immediate problem is that Julia comes with patches for LLVM 3.9
only:

  https://github.com/JuliaLang/julia#llvm

it downloads, patches and compiles a specific LLVM. We actually need
this even though the failing tests are possibly not related (I suspect
the math libraries are not showing the same results as the built-in
ones).

I think we need to follow the recommended build steps for Julia first.
Then the tests should pass. Next perhaps link out components and send
bug reports upstream.

Pj.