Android: Fix OpenJDK 7 package sign.

Add "-digestalg SHA1 -sigalg MD5withRSA" to jarsign parameters as suggested by
https://code.google.com/p/android/issues/detail?id=19567

Change-Id: I0c809517d8cd3b1225b6a557f9f91227dbf42cf9
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>
Reviewed-by: Daniel Teske <daniel.teske@digia.com>