Fix the type of umask to file_perm -> file_perm

[favonia]

It seems file_perm should be used in the type of Unix.umask. (It's currently an alias of int, so this does not really change the API except for its documentation.)

[shindere]

This change looks clearly sensible and an improvement to me. While we are at it, I wondered whether the type for file masks should be different from the type for file modes, although the two are boviously tightly related. I checked how things are done in Haskell and found tha the `setFileCreationMask` funciton does not seem to distinguish file modes from masks so this suggests it's okay to do like this or, at least, if it's not, well we won't be the only ones not doing things the right way.

[shindere]

Just two things before this gets merged, please. 1. I think the PR is worth a Changes entry, which should fix the Hygien workflow. 2. While you are at it, could you please, at least in the commit message, prefix `umask` and `file_perm` with the name of the Unix module they belong to, for increased readability?

[favonia]

Done

[shindere]

favonia (2022/08/08 04:41 -0700):

Done

Thanks! I jsut merged. I am a bit unsure about the section of Changes to which this should belong. I understand that for now there is no API change so it makes sense to add it to the manual section. Still, I was tempted to add it to the `Other libraries` section but I'll leave this decision to our Changes masters, @gasche and @Octachron.