code generation. Variables addressed through a GlobalAlias were not being
handled, and variables with available_externally linkage were treated
incorrectly. The patch contains two new tests to verify the correct code
generation for these cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171778 91177308-0d34-0410-b5e6-96231b3b80d8