This would assert if a constant address space was extern
and therefore didn't have an initializer. If the initializer
was undef, it would hit the unreachable unhandled initializer case.
An extern global should never really occur since we don't have
machine linking, but bugpoint likes to remove initializers.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210967 91177308-0d34-0410-b5e6-96231b3b80d8