Bug 923950 - Fix Android single locale repacks. r=glandium

There are two parts to this.  The first is to add AndroidManifest.xml
as a dependency to the "no dependencies" ap_ built during packaging.
The aapt call requires it.  So "no dependencies" is more accurately
"no *resource* dependencies".

The second is to avoid including the Android res/ directory in the
language repack step.  What happens is that the l10n.py script sees
the Android res/ files left in the dist/ directory after unpacking and
expects to find them in the objdir.  They're not there, so the script
fails.  To avoid this, we delete them after unpacking.  See the
comments in packager.mk describing this process.

--HG--
extra : rebase_source : 35c3c125dddcd575c1a5e8ad58f9aa13ff2db4c3