The 'ostree' binary is not available as an installable
package on Ubuntu. Instead of requiring users to build
it from the source code, lets add a native ostree binary
to the toolchain.

Change-Id: I50031e0fc72bc0585785634a329d1557876a020b
Reviewed-by: Samuli Piippo <samuli.piippo@theqtcompany.com>