Move SDK system-image source.prop_templates in their own folder.

This allows to have a different rule to generate the source.properties
based on the templates and place them in a directory that depends on
the current target CPU ABI. In turn this prevents the build from
mixing different source.props when building different targets.

Change-Id: I4a1d9f47426c94f376947ddae8be9f5549331616
14 files changed