Ignore all hidden files when scanning for BUILD files.
Ignore all hidden files when scanning for BUILD files.

Hard to believe we didn't already have this in our defaults.
Upstream has '*' in the defaults, but we override those.

(sapling split of 728793a8858f3c889a8a255f0f37ed9921caad52)
foursquare/fsqio,foursquare/fsqio,foursquare/fsqio,foursquare/fsqio,foursquare/fsqio