Add files to build on Android

Add files to build on Android

The Android.mk files were taken from the Android AOSP sources, and
updated for the 1.43 next branch.  The intention is that this will
allow the repository which is currently located in external/e2fsprogs
with one which is based off of the upstream e2fsprogs.  Right now
external/e2fsprogs was not created using "git clone", so it means that
git merges don't work.  After the external/e2fsprogs Android
repository is replaced, with one based off the upstream repository,
Android will be able to synchronize with the upstream repository by
pulling and merging from upstream, and then running the script
"./util/gen-android-files" to update any generated files.  (This is
necessary because in the Android build system, the Android.mk files
are rather stylized and don't make it easy to run arbitrary shell
scripts during the build phase.)

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>