The Viewer app is intended to eventually resemble the experimental
Android DocumentLoader app.
Build using the gbuild mechanism, which is also invoked from an Xcode
project. This seems to work out fine, the resulting app installs at
least on the simulator, and you can debug all the LO code involved
even if Xcode (obviously) has no knowledge of the LO source
files/classes/etc.
Change-Id: Ic96178d80b8d6467cac969b29e37f0d39513acf9