RRO tests: adapt tests to split apks

The introduction of support for split apks has resulted in the move of
applications from /partition/app/pkg.apk to /partition/app/pkg/pkg.apk.
Update the RRO testrunner to use the new paths.

Bug: 17765434
Change-Id: I6eebfb6f879404077b9447c750ddc395ecd9a547
RRO tests: fix potential NPE

Bug: 17765434

Check for null before closing streams.

Change-Id: I651785649575725009f270d4d8eb5f4bf90952a6
RRO idmap: pad with 0xffffffff, not 0x00000000

In the new idmap format (version 0x1), 0x00000000 no longer represents a
non-existing entry: 0xffffffff should be used instead.

Bug: 17765434
Change-Id: If2c7e09feba2224eeafe88fd9230e6392d81b9a7
RRO: reintroduce lost ResTable insert of assets

With the recent introduction of AssetManager::appendPathToResTable,
overlay packages were not properly added to the AssetManager, and once
added, were not properly inserted into the ResTable.

Bug: 17765434
Change-Id: Ie21f227c654c98730f74a687d0e16ee2b80e747e
RRO: prevent duplicate system overlays

System overlays, ie overlays with targetPackage="android", were loaded
twice, which caused all sorts of issues. Ensure they are only loaded
once, which will be during Zygote initialization.

Bug: 17765434
Change-Id: Ia5064045c77f713c58fb78adc3942f6af1abdc93