chg: enable clang-format on all .c and .h files
Nothing in here looks awful, so I think we may as well just do it.
# skip-blame because it's just reformatting with no functionality change
Differential Revision: https://phab.mercurial-scm.org/D2058
python3: whitelist an additional 11 tests
I think these are mostly the result of Pulkit's recent work. Thanks!
Differential Revision: https://phab.mercurial-scm.org/D2078