[ThinkLTO] Invoke build(Thin)?LTOPreLinkDefaultPipeline.

Previously it doesn't actually invoke the designated new PM builder
functions.

This patch moves NameAnonGlobalPass out from PassBuilder, as Chandler
points out that PassBuilder is used for non-O0 builds, and for
optimizations only.

Differential Revision: https://reviews.llvm.org/D34728

llvm-svn: 306756