Master of Orion 1 an 2 fail to run due to steam dosbox missing libcaca.

**Game information**
Master of Orion 1 and 2 at the very least

**Distribution name and version where applicable**
Debian Buster. 10.3, x86_64.

**Flatpak info**
$ flatpak --version
Flatpak 1.6.2
$ flatpak --gl-drivers
default
host

**Problem description**
Games that rely on dropbox as a steam runtime fail to run. Looking at steam output after running it in a console with `flatpak run com.valvesoftware.Steam` I see:

```
/home//.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/dosbox_x86_64: error while loading shared libraries: libcaca.so.0: cannot open shared object file: No such file or directory
Done.
```

ldding the dosbox binary after entering the flatpak with a bash shell (`flatpak run --command=/bin/bash com.valvesoftware.Steam
`) shows other libraries missing as well

```
ldd /home//.local/share/Steam/steamapps/common/Master\ of\ Orion\ 1/dosbox/dosbox_x86_64 | grep 'not found'
libSDL_sound-1.0.so.1 => not found
libSDL-1.2.so.0 => not found
libpng12.so.0 => not found
libSDL_net-1.2.so.0 => not found
```

however these libraries seem to be shipped next to dosbox

```
find /home/alex/.local/share/Steam/steamapps/common/Master\ of\ Orion\ 1/dosbox/libs/x86_64/ -type f
/home/alex/.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/libs/x86_64/libSDL_net-1.2.so.0.8.0
/home/alex/.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/libs/x86_64/libsmpeg-0.4.so.0
/home/alex/.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/libs/x86_64/libSDL-1.2.so.0
/home/alex/.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/libs/x86_64/libSDL_sound-1.0.so.1
/home/alex/.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/libs/x86_64/libSDL-1.2.so.0.11.4
/home/alex/.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/libs/x86_64/libpng12.so.0
/home/alex/.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/libs/x86_64/libpng12.so.0.50.0
/home/alex/.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/libs/x86_64/libmikmod.so.2.0.4
/home/alex/.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/libs/x86_64/libSDL_sound-1.0.so.1.0.2
/home/alex/.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/libs/x86_64/libSDL_net-1.2.so.0
/home/alex/.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/libs/x86_64/libmikmod.so.2
/home/alex/.local/share/Steam/steamapps/common/Master of Orion 1/dosbox/libs/x86_64/libsmpeg-0.4.so.0.1.4
```

by steam. Turns out the libcaca error is from libSDL-1.2.so.0.11.4 (libSDL-1.2.so.0 is the exact same binary) that user libcaca library and fails to find it.

```
ldd dosbox/libs/x86_64/libSDL-1.2.so.0 |grep 'not found'
libcaca.so.0 => not found
```

**Does this issue reproduce with native Steam**
Have not tested but reports in user channels and wikis point out that steam uses the system's libcaca. e.g.

https://wiki.archlinux.org/index.php/Steam/Game-specific_troubleshooting#Rock_Boshers_DX:_Directors_Cut suggests installing 32-bit version of libcaca

https://steamcommunity.com/app/410980/discussions/0/343787920130132180/ points out to problems being resolved once libcaca and speex is installed in the system

https://github.com/ValveSoftware/steam-for-linux/issues/553#issuecomment-12097292 points out that this is known since 2013 and possibly fixed by dropping the dependency?