Maciej S. Szmigiero authored Feb 19, 2023 and Philip Withnall committed Feb 21, 2023

All Unix CRTs examined: glibc, musl, BSDs, Apple libc, Android bionic
ignore unknown fopen () mode flags, so this flag can be added
unconditionally for Unix builds.

Only Windows CRT is intolerant of these, so the single case in
g_dbus_address_connect () where the fopen () call is shared between Unix
and Windows needs appropriate platform-specific handling.

Skipped the call sites in libcharset and xdgmime copylibs.