tests: fix inline extension bytes in test-ssh-proto-unbundle.t
# skip-blame just b prefixes
Differential Revision: https://phab.mercurial-scm.org/D2610
hghave: fix up clang-libfuzzer regex to be bytes
Fixes this check on Python 3.
# skip-blame just a b prefix
Differential Revision: https://phab.mercurial-scm.org/D2607