Bug 1021: OVR GlueGen Mapping: Compile all generated C files, add missing C ovrHmdStruct in generated files, reduce warnings.
Bug 1021: OVR GlueGen Mapping: Handle non-existent native oculusvr lib gracefully

- query isAvailable() in ovr_Initialize(), ovrHmd_Create(..) and ovrHmd_CreateDebug(..)
  and return appropriate values.