add not working input for bucketsort impl.

The following input contains uniform distributed character, but breaks the
reference implementation (because buckets overflow).
So the question is, what uniform distribution means in this context.

c_sequential/bucketsort/input/uniform.rb

@@ -0,0 +1,13 @@
+#!/usr/bin/env ruby
+
+puts 94 * 94
+('!'..'R').each do |c1|
+  ('!'..'~').each do |c2|
+    print c2 * 4, c1 * 3, "\n"
+  end
+end
+('S'..'~').each do |c1|
+  ('!'..'~').each do |c2|
+    print c1 * 3, c2 * 4, "\n"
+  end
+end