Log Message:
ncdu: update to 1.15.1.

1.15.1 - 2020-06-10

- (Linux) Fix build on older Linux systems (Christian Gottsche)
- (MacOS) Revert "Exclude firmlinks by default" behavior (until we have
  a better solution)
- (MacOS) Add --exclude-firmlinks option to opt-in to the above behavior

1.15 - 2020-05-30

- (Linux) Add --exclude-kernfs option to exclude pseudo filesystems (Christian
  Gottsche)
- (MacOS) Exclude firmlinks by default (Saagar Jha)
- (MacOS) Add --follow-firmlinks option to follow firmlinks (Saagar Jha)
- Fix bug in calculating the apparent size of directories containing hardlinks
- Fix integer overflow with directories containing >2GiB worth of file names
- Fix yet another possible 100% CPU bug when losing terminal