Random Number Generator Refactoring (removing from Module)

This patch removes the RNG from Module. Passes should instead create a new RNG for their use as needed.

Patch by Stephen Crane @rinon.

Differential revision: http://reviews.llvm.org/D4377

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224444 91177308-0d34-0410-b5e6-96231b3b80d8