In mergeVisibility, if we already have an explicit visibility, keep it.
This fixes the included testcase and lets us simplify the code a bit. It
does require using mergeWithMin when merging class information to its
members. Expand the comments to explain why that works.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@155103 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed