The rmtypedefs tool is inteded only for the Android build itself.
It is given a set of .class file folders, and it finds any .class
files within those folders that correspond to "typedef annotations":
these are annotation classes that themselves have been annotated with
@IntDef or @StringDef. These typedefs should all be using
@Retention(RetentionPolicy.SOURCE), something this tool will check and
report if not the case.
However, even if an annotation only has source level retention, the
annotation class *itself*, will still be created as a .class file. We
don't want these annotations in the Android system image, so this tool
is used to find and nuke the corresponding .class files for the
annotations themselves.
Change-Id: Ia343cc5bdbf215ded24b4354f3d92f5a9076eae3
