test/dtrace/test_method_cache.rb: avoid spewing too much

Don't output method cache clearing at startup since
it causes dtrace to drop output and break the test.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63579 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/dtrace/test_method_cache.rb

@@ -19,7 +19,7 @@ module DTrace
     def probe
       <<-eoprobe
 ruby$target:::method-cache-clear
-/arg1/
+/arg1 && arg2/
 {
   printf("%s %s %d\\n", copyinstr(arg0), copyinstr(arg1), arg2);
 }