Need to set locale.textdomain under linux

[romjerome]

_build_popup_ui() ignores translated strings without locale.textdomain set.

[romjerome]

@jralls
I do not know if we need to set locale.textdomain
under MacOS too, for avoiding a specific issue
around context menu on Editors (Person, Family).

See also bug report 12278.

[jralls]

@romjerome This does set the text domain for macOS, the conditional is if not sys.platform == 'win32' and macOS isn't win32.

[romjerome]

@jralls
Sorry, as the proposal makes the change for macOS too, I just wonder if this issue was specific to linux or both OS should have the fix. I do not have a macOS available now for testing...
macOS could have a specific handling for GLib's g_dgettext wrapper (or so) and only linux os should have the fix.
I just want to avoid a bug for macos users in relation with this section.

[jralls]

@romjerome, there's very little macOS customization in glib. I tested on macOS: It does have the problem and this fixes it.

[romjerome]

Thanks!
I will commit the change and close BR12278