test/io/console/test_io_console.rb (test_oflush): Avoid race condition

Add a ad-hoc wait.  Follows test_ioflush2.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62411 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/io/console/test_io_console.rb

@@ -212,6 +212,7 @@ defined?(PTY) and defined?(IO.console) and TestIO_Console.class_eval do
       s.oflush # oflush may be issued after "a" is already sent.
       s.print "b"
       s.flush
+      sleep 0.1
       assert_include(["b", "ab"], m.readpartial(10))
     }
   end