allow suite.pm to skip combinations that originate from test/include files.

storage/innobase/handler/handler0alter.cc:
  for NEWDATE key_type says unsigned, thus col->prtype says unsigned,
  but field->flags says signed. Use the same flag for value retrieval
  that was used for value storage.

mysql-test/lib/My/Suite.pm

@@ -5,6 +5,7 @@ package My::Suite;
 
 sub config_files { () }
 sub servers { () }
+sub skip_combinations { () }
 
 sub list_cases {
   my ($self, $testdir) = @_;