s/S_IWRITE/S_IWUSR/

[kmk3]

They are equivalent, but only the latter is POSIX. See sys_stat.h(0p)
of POSIX.1-2017[1]. From Section 14.9.5, The Mode Bits for Access
Permission of the glibc manual[2]:

S_IWUSR
S_IWRITE

Write permission bit for the owner of the file.  Usually 0200.
S_IWRITE is an obsolete synonym provided for BSD compatibility.

Current usage:

$ git grep -F S_IWRITE -- src | wc -l
11
$ git grep -F S_IWUSR -- src | wc -l
26

Commands used to search and replace:

$ git grep -l -z S_IWRITE -- src | xargs -0 -I '{}' sh -c \
  "printf '%s\n' \"\`sed 's/S_IWRITE/S_IWUSR/g' '{}'\`\" >'{}'"

Note: The other related non-POSIX macros are not used anywhere:

$ git grep -F -e S_IREAD -e S_IEXEC -- src
$

[1] https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_stat.h.html
[2] https://www.gnu.org/software/libc/manual/html_node/Permission-Bits.html

---

Misc: I noticed this on #4586.

Since this conflicts with #4586, I'm marking this as a draft until that is
merged.

Note to self: This will need to be rebased/reworded.

[smitsohu]

Since this conflicts with #4586, I'm marking this as a draft until that is
merged.

Resolved in that pull request. Looks good!

[kmk3]

@smitsohu commented on Oct 5:

Since this conflicts with #4586, I'm marking this as a draft until that is
merged.

Resolved in that pull request.

Nice.

Looks good!

Thanks!

[netblue30]

All fine, the worst that can happen is to break the compilation on some old systems. I'm merging it in.