www/firefox-esr: expose PipeWire support after c58401d4dda5

Should work on wlroots-based compositors. For example,

1. pkg install firefox sway pam_xdg xdg-desktop-portal-wlr xdg-desktop-portal
2. sysrc seatd_enable=YES
3. service seatd start
4. echo 'session optional pam_xdg.so notroot runtime' >>/etc/pam.d/system $ exit # log out to pick up XDG_RUNTIME_DIR <new login> $ export XDG_CURRENT_DESKTOP=sway $ export MOZ_ENABLE_WAYLAND=1 $ dbus-daemon --session --fork --address=unix:runtime=yes $ sway <GUI session> $ dbus-update-activation-environment --all $ daemon -f pipewire $ firefox https://mozilla.github.io/webrtc-landing/gum_test.html <click on "Screen Capture"> <select "Use operating system settings"> <click on "Allow" button> <select via cursor the desired screen (output display)> <notice the screen mirrored on the web page>