Support "preserving" the summary information when using setModule() API in LTOCodeGenerator

Another attempt at r267655...

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267665 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed