Fix android recipe linking with Qt bootstrap

[lazycat11]

Summary

• link the android recipe extension against the Qt bootstrap's arch-specific main library name
• keep the existing main fallback for non-SDL, non-Qt bootstraps
• include the bootstrap libs directory in ANDROID_LIBS_DIR for Qt bootstrap outputs

Root cause

The Qt bootstrap builds its native entry library as libmain_.so, while the android recipe's setup.py defaulted to linking non-SDL bootstraps with -lmain. This can fail when building the android recipe with the Qt bootstrap because libmain.so is not produced there.

Validation

• python -m flake8 pythonforandroid/recipes/android/init.py pythonforandroid/recipes/android/src/setup.py
• python -m py_compile pythonforandroid/recipes/android/init.py pythonforandroid/recipes/android/src/setup.py
• python -m pytest tests/test_recipe.py -q
• Fork CI run 25206705650: Flake8, Java Spotless, Build test APP [ubuntu-latest | qt], and all Test updated recipes jobs passed

Note: the fork CI documentation job failed twice due to linkcheck timing out on https://pastebin.ubuntu.com/, which is unrelated to this change.