LLVM 3.5 rebase

[Jens Petersen]

> That's only going to work if llvm34 renames all of its binaries, and ghc
> is changed to invoke the renamed ones, right?  Otherwise the 3.4 and 3.5
> versions of /usr/bin/llc will conflict.

Hmm yes I guess I should go the whole way...

My initial lazy plan was just that ghc-compiler.armv7hl
should require and BR llvm34 instead of llvm (and make llvm34
Conflicts with llvm and llvm34-devel conflicts with llvm-devel...).

Not sure how many people really need both (on arm),
but I suppose it is better to avoid conflict where possible.

Jens