In !7069 (merged) we used CMAKE_ANDROID_API to check the Android API
level. However, CMAKE_SYSTEM_VERSION is the authoritative value.
When cross-compiling for Android, an unset CMAKE_ANDROID_API can result
in failure to locate JNI because the NativeHelper component cannot be
found. In this case, the component is falsely assumed to be available by
default (and thus required) since the comparison against an unset
CMAKE_ANDROID_API variable evaluates to true. Use CMAKE_SYSTEM_VERSION
to determine the Android API level instead.
Issue: #23830 (closed)
Backport: release
Topic-rename: FindJNI-android-api