It is better to add a comment rather than simply disabling these 2 calls without
explanation on macOS. This way, developers who'll look at this code in the
future will immediately know what's the reason and status for the "unicity"
concept of GIMP process on macOS. Basically there are 3 features:
- Opening files from another software (such as "open with" in file browsers)
which is handled differently in macOS and apparently works fine. It looks like
it works by handling system signals, connected from gui_unique_quartz_init().
- Opening files by running a new GIMP process which would pipe the filenames
into an existing GIMP process before immediately exiting.
- Running batch process in an existing GIMP process, also by running a short-run
GIMP process.
The last 2 features are simply now officially disabled in macOS because dbus is
not installed by default and seem like it may cause issues when it is.
See discussions in !808 and #8997.
(cherry picked from commit 68cd873481)
c25dd4e739