LP:688404 - pbxt crashes on Windows 64 (misalignment on SSE instruciton)

In Maria 5.2 PBXT crashes directly on startup
with this callstack.

mysqld.exe!_setjmp()
mysqld.exe!xt_create_thread()[thread_xt.cc:1425]
mysqld.exe!xt_init_threading()[thread_xt.cc:1211]
mysqld.exe!pbxt_init()[ha_pbxt.cc:1203]
mysqld.exe!ha_initialize_handlerton()[handler.cc:431]
...

Disassembly reveals sse instruction that requires 16 bit aligment on misaligned address.