Dist module stub libraries for in sdk builds

Makes the stub libraries accessible to update_prebuilts.py,
so they can be finalized together with their txt files (already dist'd).

Bug: 149293194
Test: m dist sdk && find out/dist -name 'framework-*.jar'
Change-Id: Id4070113bf786bf79573d7b29cd98fcd86e20851
Merged-In: Id4070113bf786bf79573d7b29cd98fcd86e20851
(cherry picked from commit 5259a14d)