Split this test case into three cases. globalredefinition.ll just tests
that a global can be forward referenced. globalredefinition2.ll tests
that llvm-upgrade will warn about renaming duplicate global variables.
globalredefinition3.ll tests that llvm-as will generate an error on
duplicate global variables. This last test is currently XFAIL because
the restriction is not implemented yet.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@32910 91177308-0d34-0410-b5e6-96231b3b80d8
