Add rules for packaging up Ruby code.

These were originally written by Parker and then cleaned up by me.

Change-Id: I93b66c83f80ca86a267abb84cab5f160b837083b
diff --git a/build_tests/ruby_check.sh b/build_tests/ruby_check.sh
new file mode 100755
index 0000000..70d3149
--- /dev/null
+++ b/build_tests/ruby_check.sh
@@ -0,0 +1,14 @@
+#!/bin/bash
+
+# Checks the output from ruby.rb.
+
+set -e
+set -u
+
+OUTPUT="$("./build_tests/ruby_binary" "${PWD}")"
+
+if [[ "${OUTPUT}" != "Hi from ruby" ]]; then
+  echo "Output is actually:" >&2
+  echo "${OUTPUT}" >&2
+  exit 1
+fi