Distclean improvements

[softins]

Short description of changes

Adds to Jamulus.pro rules to delete generated directories when doing a make distclean

The object is to return the tree to the state it would be after git clone by removing anything generated,
but not touching anything manually added such as libs/ASIOSDK2 or local files.

CHANGELOG: Build: improve make distclean to remove leftover files and directories.

Context: Fixes an issue?

Fixes #3878

Does this change need documentation? What needs to be documented and how?

No

Status of this Pull Request

Ready. Tested on Linux, Mac and Windows

What is missing until this pull request can be merged?

• Testing in Android build environment.
• Testing in iOS build environment.

Checklist

• I've verified that this Pull Request follows the general code principles
• I tested my code and it does what I want
• My code follows the style guide
• I waited some time after this Pull Request was opened and all GitHub checks completed without errors.
• I've filled all the content above

AUTOBUILD: Please build all targets

[pljones]

• Testing in Android build environment.

If you can run the Linux build, it's possible to run the Android build using the same tool chain as Github (you need lots of libraries and compilers installed, of course).

I should be able to try it later on, anyway.

Once you've got the libraries...

#!/bin/bash
export ANDROID_NDK_ROOT=/usr/lib/android-sdk/ndk/21.0.6113669
export QT_SELECT=5.15.2-android

# make distclean || :
qmake Jamulus.pro -spec android-clang ANDROID_ABIS=arm64-v8a
make INSTALL_ROOT=android-build install
# make clean || :

[pljones]

OK, so I ran the android build:
after-disclean-improvements.log

The make distclean worked perfectly as far as I could tell.