Bug 226121

Please enable printing and webRTC support as already enabled in the TrueOS version of the port:

The changes were committed to the TrueOS tree in a few batches:
 * [Enable basic printing and WebRTC](https://github.com/trueos/freebsd-ports/commit/1b49a8d09d09429196d6636c379f755d9da54b49)
 * [Enable print-preview/pdf and fix pulseaudio option](https://github.com/trueos/freebsd-ports/commit/eeaf2cccf0a2a43081709125539a3d05a5236d45)
 * [Enable plugins and widevine support capabilities](https://github.com/trueos/freebsd-ports/commit/9aeba4d5c0359b3ed675a2fd59d52aaaa4e6ae2b)

The end result though is that "files/freebsd.pri" just needs to get adjusted to match the following:

```
include(desktop_linux.pri)

gn_args +=   disable_nacl=true           \
             enable_basic_printing=true \
             enable_print_preview=true \
             enable_pdf=true \
             enable_webrtc=true   \
             enable_hidpi=true      \
             use_dbus=true           \
             enable_plugins=true	\
             enable_widevine=true

# Once the port works better, we can think about readding the diverse `use_system_<foo>`
# for bundled libraries.
# For now, only add very few system libraries.
gn_args += use_system_yasm=true   \
           use_system_libusb=true \
           use_system_libcxx=true
```

And the "printsupport" module needs to get added to the USE_QT5 macro list in the Makefile.