Delete examples/llama.android/llama/CMakeLists.txt (#8165)

* Delete examples/llama.android/llama/CMakeLists.txt

https://github.com/ggerganov/llama.cpp/pull/8145#issuecomment-2194534244

This file is not being used for building on Android. `llama.cpp/examples/llama.android/llama/src/main/cpp/CMakeLists.txt` is being used instead.

* Update CMakeLists.txt

Pick local llama.cpp files instead of fetching content from git