Remove old generator code

We're generating Android.bp from BUILD.gn, so no need for the old
version.

Change-Id: Ie5bcec1d4f15d0e9a178feb9191e42c872bd8e08
Reviewed-on: https://skia-review.googlesource.com/7639
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
8 files changed