Fix:toolchain:Remove privileged operation from build script

[mvglasow]

As mentioned in #827, this PR moves privileged operations (sudo apt-get install) out of the build script, replacing it with a check if the required component is installed (if it is not, the script will abort with an error).

For local builds, you need to install ant yourself. If you haven’t done so before starting the build, the script will abort with a meaningful error message.

For CircleCI, ant has been added to the list of packages to install.

On F-Droid this will be a separate merge request (Link will follow).

[mvglasow]

@jandegr could you take a look at this as well, just to make sure I am not inadvertently breaking anything?

[mvglasow]

And the related F-Droid merge request is at https://gitlab.com/fdroid/fdroiddata/merge_requests/5289

[pgrandin]

I think that it makes sense 👍

[jkoan]

Perfect!
Personally I like the the longer if else construct more, but it is perfectly fine how it is now

[lains]

Oops, I hadn't seen @jkoan's comment that is probably exactly saying the same thing...

[lains]

Maybe this line good be written in a way that is more compatible with generic shell syntax like:

if which ant >/dev/null; then
    echo "FATAL: ant is not installed; install manually and retry." >&2
    exit 1
fi

[mvglasow]

This will fail if ant is found and succeed if it is not found (just tried it). I am not a shell guru, though; all I know is that anything involving shell scripts and success/failure/true/false/if is highly confusing.

Redirecting to stderr is a good point, though.

[lains]

Mmm... OK, I missed the fact that there is an issue because of the mix of if then construct and set -e