Add vendor/google/prism

Change-Id: I88f2653bd74718ef962042f1de45d46dc1484014
diff --git a/default.xml b/default.xml
index f3f0aa1..5a77f59 100644
--- a/default.xml
+++ b/default.xml
@@ -40,6 +40,7 @@
   <project name="vendor/google/jtux"/>
   <project name="vendor/google/mpegparser"/>
   <project name="vendor/google/platform"/>
+  <project name="vendor/google/prism"/>
   <project name="vendor/google/sagejni"/>
   <project name="vendor/google/sageserver"/>
   <project name="vendor/google/swscale"/>