Our C coding style requires to use spaces for formatting. However, there are over 300 files using tabs:

$ fgrep -lr $'\t' . --include=*.[ch] | wc -l
     367

Many of these uses are inconsistent or mix tabs and spaces.

1. We should make a one-time change to replace all tabs with spaces and
2. Add a check that new PRs don't introduce new Tabs by running a check in one of our dist/s_* scripts (could be a separate ticket and PR).