Make ABI mismatch a warning (ROOT-5961).
Make ABI mismatch a warning (ROOT-5961).

karies/cling,marsupial/cling,marsupial/cling,karies/cling,perovic/cling,root-mirror/cling,root-mirror/cling,karies/cling,perovic/cling,karies/cling,marsupial/cling,root-mirror/cling,perovic/cling,perovic/cling,marsupial/cling,marsupial/cling,karies/cling,root-mirror/cling,marsupial/cling,root-mirror/cling,karies/cling,perovic/cling,root-mirror/cling