manifest: improve filesnotin performance by using lazymanifest diff
lazymanifests can compute diffs significantly faster than taking the set
of two manifests and calculating the delta.
when running hg diff --git -c . on Facebook's big repo, this reduces the
run time from 2.1s to 1.5s.
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true