Google severally provide lists of symbols exported by libc, libm, libdl, and related NDK libraries by older Android releases, at this URL, which might be a welcome resource for Gnulib developers:
https://android.googlesource.com/platform/development/+/refs/heads/marshmallow-release/ndk/platforms in which the number in each subdirectory is the value of __ANDROID_API__ specifying the version pertained to, and symbol lists for libraries on each supported architecture are saved under "arch-*/symbols."
