[ThinLTO] Internalize readonly globals

This patch allows internalising globals if all accesses to them
(from live functions) are from non-volatile load instructions

Differential revision: https://reviews.llvm.org/D49362


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346584 91177308-0d34-0410-b5e6-96231b3b80d8
42 files changed