[llvm] [flang-rt] fix missing llvm_gtest target (PR #67936)

[Maksim Levental via llvm-commits]

makslevental wrote:

@mizvekov I don't work on flang so I'm not sure the correct for them - I just put this up as essentially a "hotfix". The alternative unblock is to revert that big `flang-rt` patch right?

https://github.com/llvm/llvm-project/pull/67936