app portgroup have x11 application not bounce indefinitely

[elelay (Eric Le Lay)]

(Following #39613)

There is an option that can be set in the playlist so that no doc icon is created for a graphical application:

<key>LSUIElement</key>
<string>1</string>

This is useful when building x11 gtk apps because they never signal the windowing system that they have launched and the associated icon keeps bouncing forever.

It would be nice to generate this into the plist depending on a boolean option of the app portgroup.

Overwise I add following code in my Portfile:

    if {![variant_isset quartz]} {
        reinplace -E {s|(<string>APPL</string>)|\1 <key>LSUIElement</key><string>1</string>|} \
                 "${destroot}${applications_dir}/Quodlibet.app/Contents/Info.plist"
    }