Bug#977857: libreoffice-common: On Wayland, it doesn't work without the xwayland pkg but installation does not pull xwayland as a dependency

[jman <dpt@storiepvtride.it>]

Package: libreoffice-common
Version: 1:7.0.4~rc2-1
Severity: normal

Dear Maintainer,

I have installed Libreoffice on a Wayland+Sway system without any X11 package (included xwayland).

Upon starting libreoffice I get an error because the display :0 is tried:

```
$ soffice --version
LibreOffice 7.0.4.2 00(Build:2)

$ soffice
/usr/lib/libreoffice/program/soffice.bin X11 error: Can't open display:
   Set DISPLAY environment variable, use -display option
   or check permissions of your X-Server
   (See "man X" resp. "man xhost" for details)
```

I tried setting these env vars but it didn't work:

```
export _JAVA_AWT_WM_NONREPARENTING=1
export MOZ_ENABLE_WAYLAND=1
export QT_QPA_PLATFORM=wayland-egl
export QT_QPA_PLATFORMTHEME=qt5ct
export QT_WAYLAND_FORCE_DPI=96
export QT_WAYLAND_DISABLE_WINDOWDECORATION=1
export SDL_VIDEODRIVER=wayland
export SAL_USE_VCLPLUGIN=gtk3
```

In order to make Libreoffice work, the package `xwayland` should be installed as a dependency.

Unless I'm wrong, I believe the real issue is that Libreoffice does not work on a pure Wayland
installation, but this fact is not very clear to the user. I've tried searching for related issue on
the Libreoffice buttracker but found none.

Suggestion: make `xwayland` a required dependency of Libreoffice until the day that Libreoffice does
not need Xorg anymore.

Thanks,

-- Package-specific info:

-- System Information:
Debian Release: bullseye/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.9.0-4-amd64 (SMP w/8 CPU threads)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages libreoffice-common depends on:
ii  libnumbertext-data         1.0.6-1
ii  libreoffice-style-colibre  1:7.0.4~rc2-1
ii  ucf                        3.0043
ii  ure                        1:7.0.4~rc2-1+b1

Versions of packages libreoffice-common recommends:
ii  apparmor            2.13.5-1+b2
ii  fonts-liberation2   2.1.1-1
ii  libexttextcat-data  3.4.5-1
ii  python3-uno         1:7.0.4~rc2-1+b1
ii  xdg-utils           1.1.3-2

Versions of packages libreoffice-common suggests:
ii  libreoffice-style-colibre [libreoffice-style]  1:7.0.4~rc2-1

Versions of packages python3-uno depends on:
ii  libc6                    2.31-5
ii  libgcc-s1                10.2.1-1
ii  libpython3.9             3.9.1-1
ii  libreoffice-core         1:7.0.4~rc2-1+b1
ii  libstdc++6               10.2.1-1
ii  libuno-cppu3             1:7.0.4~rc2-1+b1
ii  libuno-cppuhelpergcc3-3  1:7.0.4~rc2-1+b1
ii  libuno-sal3              1:7.0.4~rc2-1+b1
ii  libuno-salhelpergcc3-3   1:7.0.4~rc2-1+b1
ii  python3                  3.9.0-4
ii  python3.9                3.9.1-1
ii  ucf                      3.0043
ii  uno-libs-private         1:7.0.4~rc2-1+b1

-- no debconf information