Add opencv armhf tarball

It won't work very well for other architectures yet, but it generates
binaries which run on raspbian just fine.

Jim started this, and then I hacked things a bit to make it work.

Change-Id: Iff376f3e27e700d05320c529a401b518a132e44a
diff --git a/debian/BUILD b/debian/BUILD
index 5c9d814..11f9349 100644
--- a/debian/BUILD
+++ b/debian/BUILD
@@ -48,6 +48,10 @@
     ":python_gtk.bzl",
     python_gtk_debs = "files",
 )
+load(
+    ":opencv_armhf.bzl",
+    opencv_armhf_debs = "files",
+)
 load("//debian:packages.bzl", "download_packages", "generate_deb_tarball")
 
 filegroup(
@@ -282,6 +286,13 @@
     files = python_gtk_debs,
 )
 
+# This list was generated with download_packages.py on armhf and then
+# hand-tweaked to get everything it needs.
+generate_deb_tarball(
+    name = "opencv_armhf_v3",
+    files = opencv_armhf_debs,
+)
+
 exports_files([
     "ssh_wrapper.sh",
 ])