Consolidate, flavourise, update. USE_GCC because D35327.
SONAMEs/flavours:
* GTK3 + libsoup = libwebkit2gtk-4.0 (40)
* GTK3 + libsoup3 = libwebkit2gtk-4.1 (41)
* GTK4 + libsoup3 = libwebkitgtk-6.0 (60)
Switch net/remmina to the 4.1 API/flavour
Reported by: eduardo
PR: 275914