To get WebAssembly templates to actually work, we need to use
Mono 6.6 (currently in preview), which doesn't have tags yet
but is in the `2019-08` branch. So I dehardcoded the `mono-`
prefix for the git tree-ish to allow using `./build.sh 2019-08`.
6.6 doesn't build with msbuild 16.0, so I'm upgrading to its
matching version 16.3. There are no DEB files for 16.3 on the
EOL'ed Ubuntu 14.04, but it seems that the 16.04 packages install
cleanly.
We also backport a patch from mono's master branch to fix wasm
support further, and enable parallel build jobs for make.
The previous `['/bin/bash']` was not working, running the image
with `podman run -it <name>` would evaluate to:
```
> sh -c ['/bin/bash']
sh: [/bin/bash]: No such file or directory
```
We force using Emscripten 1.38.47 as there is a regression in 1.38.48
and 1.39.x which makes the generation of our .wasm file fail.
Up until now we used the desktop BCL (compiled with desktop Mono)
for both desktop and Android, but that does not work for WebAssembly
(and we suspect Android issues related to it).
So we now build the Android and WebAssembly BCLs in the relevant
containers, which are later copied in the templates directory to
include on export. We already have the desktop BCL from the regular
build.
This saves us from pulling gtk2 and gtk3 as weak deps of
perl and git or whatnot... And we don't need to pull in all
the documentation on Ubuntu.
Also ensures that we properly run `dnf clean all` after each
installation.
Rémi Verschelde
Cory Petkovsek
Hein-Pieter van Braam