- GHA/non-native: add Android builds, both cmake and autotools,
both NDK 21 (oldest available) and 35 (newest available)
https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2404-Readme.md
It comes with a maintenance burden to bump the oldest/latest values
with CI runner updates.
- cmake: disable `CURL_USE_PKGCONFIG` by default for Android.
To avoid picking up system package by default.
- build: add `ANDROID-<NDK-LEVEL>` flag to `buildinfo.txt`.
Also detect NDK level with the CMake built-in build method:
https://cmake.org/cmake/help/latest/manual/cmake-toolchains.7.html#cross-compiling-for-android
- INSTALL.md: add CMake build instructions for Android.
- INSTALL.md: make NDK levels consistent in `./configure` example.
Closes#16014