Orchestrator can build end to end.

This reduces the scope of the demo to just building and installing
a single .so, but it makes the demo actually build that single .so.

Next up, writing some unit tests and fleshing out functionality.

Test: see the README
Change-Id: I560904b786fbf69d3a83dbb08d496dba5a3192ca

orchestrator/core/ninja_runner.py

@@ -14,6 +14,7 @@
 # limitations under the License.
 
 import subprocess
+import sys
 
 def run_ninja(context, targets):
     """Run ninja.