Re-land "[LTO] Enable module summary emission by default for regular LTO"

Since we are now producing a summary also for regular LTO builds, we
need to run the NameAnonGlobals pass in those cases as well (the
summary cannot handle anonymous globals).

See https://reviews.llvm.org/D34156 for details on the original change.

This reverts commit 6c9ee4a4a438a8059aacc809b2dd57128fccd6b3.

llvm-svn: 335385