Substantially revise how clang computes the visibility of a declaration to
more closely parallel the computation of linkage.  This gets us to a state
much closer to what gcc emits, modulo bugs, which will undoubtedly arise in
abundance.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@117147 91177308-0d34-0410-b5e6-96231b3b80d8
17 files changed