CI: build images for BBB, too

This is going to burn twice as many CPU cycles (it's one more full job),
but at the same time it should ensure that there are no grave
regressions. I think it's manageable, and we might always hide it behind
a `check bbb` or something CI command in future.

Also, given that the standard build times are about 20 minutes within
the CI system, let's reduce the timw allotted for this task to a full
hour. That should still leave plenty of reserve.

Change-Id: I53034f0c7c39f791cf790cf2b3d8d2128e14f012
diff --git a/.zuul.yaml b/.zuul.yaml
index 1050daa..5b42586 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -1,7 +1,7 @@
 - job:
     name: czechlight-clearfog
     parent: run-ci-build-sh
-    timeout: 5400
+    timeout: 3600
     vars:
       prepare_git_submodules: true
     required-projects: &projects
@@ -22,7 +22,16 @@
       - github/tplgy/cppcodec
       - github/AmokHuginnsson/replxx
 
+- job:
+    name: czechlight-beagleboneblack
+    parent: run-ci-build-sh
+    timeout: 3600
+    vars:
+      prepare_git_submodules: true
+    required-projects: *projects
+
 - project:
     check:
       jobs:
         - czechlight-clearfog
+        - czechlight-beagleboneblack