MC/Mach-O: Factor out isSymbolLinkerVisible method; "linker visible" is a made up term to refer to non-temporary labels + temporary labels in sections-which-require symbols. For Darwin, it corresponds to symbols which effectively define an atom.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98923 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed