The existing ctests cannot be simply used in Android tests because
everything is compiled as standalone executable with `main()` function.
Since Android 11+ does not support standalone executables, those test
`main()` functions are converted as unique functions and then picked up
in this test's native-lib CMakeLists.txt.
Since those tests depend on libfluidsynth internals, we cannot simply
link with libfluidsynth.so. We instead compile the library with OBJ files.
gettext is known as cause of problem for running host tool in target ABI
in our builds, and the latest script still had the issue.
https://github.com/atsushieno/aap-lv2-fluidsynth/actions/runs/914453645
This fixes the problem by explicitly specifying that the build host is
x86_64 linux.
If you want to reuse the script on other platforms, you have to edit it.
