Use native-code.py generated code also for iOS.

This allows us to get rid of component-declarations.h and
simplify component-mapping.h.
For new, converted, implementation_getFactories, adding one line into
native-code.py should be enough to make them available in application.

Change-Id: I042320e5b7f8a9aa9f02b77d2bdd07cf9a690ee6
Need to have native-code.cxx as a separate file for the LibreOffice app

The executable of the LibreOffice app (which as such at the moment
doesn't work, since the tiled rendering changes) is built using
gbuild, and thus we can't generate the native-code snippet in the
CustomTarget that builds the app bundle, but need it already when
building the executable. This is one wayt to handle that.

Change-Id: Ifdab40c970e93b1f2608cefc637df8a8e5396efe
Use the same parameters to native-code.py as in TiledLibreOffice

Change-Id: If3c95562e292cb44bf9eb2de39dc66100a6fd066