skip innodb.innodb_xtradb_compat on Windows

because it tests for variables that aren't compiled for Windows,
like --innodb-priority-cleaner

mysql-test/suite/innodb/t/innodb_xtradb_compat.test

 --source include/have_innodb.inc
 --source include/have_debug.inc
 --source include/not_embedded.inc
+--source include/not_windows.inc
 
 select @@innodb_adaptive_hash_index_partitions, @@innodb_adaptive_hash_index_parts;
 --error ER_INCORRECT_GLOBAL_LOCAL_VAR