Replace gcroot verifier tests

These haven't been checking anything useful and have been testing the
wrong failure reason for many years. Replace them with something which
stresses what is actually implemented in the verifier now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@354070 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed