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_tools.py

@@ -30,6 +30,7 @@ class Ninja(ninja_writer.Writer):
         super(Ninja, self).__init__(file)
         self._context = context
         self._did_copy_file = False
+        self._phonies = {}
 
     def add_copy_file(self, copy_to, copy_from):
         if not self._did_copy_file:
@@ -43,4 +44,16 @@ class Ninja(ninja_writer.Writer):
         build_action.add_variable("out_dir", os.path.dirname(copy_to))
         self.add_build_action(build_action)
 
+    def add_global_phony(self, name, deps):
+        """Add a phony target where there are multiple places that will want to add to
+        the same phony. If you can, to save memory, use add_phony instead of this function."""
+        if type(deps) not in (list, tuple):
+            raise Exception("Assertion failed: bad type of deps: %s" % type(deps))
+        self._phonies.setdefault(name, []).extend(deps)
+
+    def write(self):
+        for phony, deps in self._phonies.items():
+            self.add_phony(phony, deps)
+        super(Ninja, self).write()
+