on windows, mariadb-5.1, built with default options (win\configure.js) - xtradb is built as dll.
On load it prints "Mutexes and rw_locks use InnoDB's own implementation"
On shutdown it crashes.
In innobase_shutdown_for_mysql() there is:
Now, btr_search_sys_free() is
It crashes later, in sync_close():
because one of the mutexes (3rd in the list) is filled with 0xFEEEFEEE. This is the value that windows uses to fill the freed memory. And this mutex is freed in btr_search_sys_free(), line 185. When I comment this line (185) out, xtradb doesn't crash anymore.