Add spacecast repo.

Change-Id: I0ae56cb7518c8515129122bdaf22e012cb8035a0
diff --git a/default.xml b/default.xml
index dfc3eaa..9fb5e90 100644
--- a/default.xml
+++ b/default.xml
@@ -56,6 +56,7 @@
   <project name="vendor/google/prism"/>
   <project name="vendor/google/sagejni"/>
   <project name="vendor/google/sageserver"/>
+  <project name="vendor/google/spacecast"/>
   <project name="vendor/google/swscale"/>
   <project name="vendor/google/tarballs"/>
   <project name="vendor/google/telepresence"/>