Fix CI builds

[derselbst]

This PR fixes the Android CI build and it (almost) fixes the Windows CI build. It also fixes fluidsynth's build on Windows XP and older.

There is one remaining issue: If a depending software package (that fluidsynth discovers via pkg-config) depends on libsndfile, fluidsynth will try to find a matching sndfile.pc file, but fails to do so, because libsndfile currently doesn't distribute them in their official Windows binary builds:
https://github.com/libsndfile/libsndfile/blob/0d3f80b7394368623df558d8ba3fee6348584d4d/.github/workflows/action.yml#L173

This will then result in the following error:
https://dev.azure.com/tommbrt/tommbrt/_build/results?buildId=11000&view=results

I currently have no explanation why this only affects the x86 while the x64 build works fine. The requirement for sndfile originates from libinstpatch's .pc file, and there sndfile is clearly marked as a requirement for both x86 and x64 builds.

@pedrolcl Do you have an idea how to fix or workaround that issue? Any idea why libsndfile has explicitly disabled installing the pkg-config file? Else I would ask them to change it.

Fixes #1422

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[pedrolcl]

Do you have an idea how to fix or workaround that issue?

You may disable libinstpatch for building this scenario. The problem may be in cmake_admin/FindInstPatch.cmake or in libinstpatch itself.

Any idea why libsndfile has explicitly disabled installing the pkg-config file? Else I would ask them to change it.

I remember requesting Erik to include the .pc file in the windows .zip package a long time ago. But since he left the project the new maintainers seem clueless, and this case in particular seems like an ideological decision.