Bug#1116212: llvm-toolchain-X.Y: please move /usr/lib/llvm* to a multi-arch co-installable location

[Matthias Klose]

I don't like the idea of moving the whole LLVM topdir 
(/usr/lib/llvm-X.Y) to a new location.

As a first step, I'd like to

  - make the runtime libs M-A: same, with having the
    real files reside in /usr/lib/<multiarch> and
    removing the files in /usr/lib/llvm-X.Y.

  - What has been in /usr/lib/llvm-X.Y in the runtime
    libs packages, is moved to the corresponding -dev
    packages, symlinking the files in /usr/lib/<multiarch>.
    And adding Breaks/Replaces.

As a second step, I'd like to see, if
/usr/lib/llvm-X.Y/lib/<multiarch> can be introduced, assuming, that 
needs adjustments for the upstream makefiles. Even if we move these 
files around manually, the RPATH for the executables has to be adjusted.

Matthias