This change adds a script which is to be called by the SwiftShader into
Android AutoRoller: https://autoroll.skia.org/r/swiftshader-android

It prepares a checkout for upload into the Android repo. Specifically,
Android does not allow remote submodules, so this script removes them.
Note SwiftShader does not require any submodules to build the library;
they are optional for development purposes.

Bug: b/189557997
Change-Id: I36b4ae59cd843f1c69146f0f52ce8f323c6bc15a
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/54768Reviewed-by: Alexis Hétu <sugoi@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>