Add generation of dependency file for .ap_ package

Add generation of dependency file for .ap_ package

Make Aapt generate a dependency file in the same directory as the
output ap_ file if the --generate-dependencies flag is set.
This dependency file can then be read by the ant exec loop task
to see whether to repackage resources.

Change-Id: I763679414daf76369700aa599c26dcf78d4de099