Change os type to match our pool

Bug: 124643718
Change-Id: Ie26b1a29c5ec338461c81dfc766af4ca200de350

infra/config/global/cr-buildbucket.cfg

diff --git a/infra/config/global/cr-buildbucket.cfg b/infra/config/global/cr-buildbucket.cfg
index 272428e..1840083 100644
--- a/infra/config/global/cr-buildbucket.cfg
+++ b/infra/config/global/cr-buildbucket.cfg
@@ -8,7 +8,7 @@
 
 builder_mixins {
   name: "linux"
-  dimensions: "os:Ubuntu-14.04"
+  dimensions: "os:Ubuntu-16.04"
 }
 
 builder_mixins {