Fix linking of unnamed_addr.

This was regression from r134829. When linking we have to be conservative. If
one of the symbols has a significant address, then the result should have it
too.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189935 91177308-0d34-0410-b5e6-96231b3b80d8