rb: Make MemoryTransport's inspect_buffer method work in Ruby 1.9

Patch: Rajesh Malepati

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@983680 13f79535-47bb-0310-9956-ffa450edef68

lib/rb/lib/thrift/transport/memory_buffer_transport.rb

@@ -88,9 +88,9 @@ module Thrift
           out << ">"
         end
       
-        out << @buf[idx].to_s(16)
+        out << @buf[idx].ord.to_s(16)
       end
       out.join(" ")
     end
   end
-end
+end