Redefine cpu's as __cpu__. Only for 6.6 branch.

src/backend/port/dynloader/bsd.c

src/backend/port/dynloader/freebsd.c

src/include/c.h

src/include/port/bsd.h

src/include/port/bsdi.h

src/include/port/freebsd.h

src/include/storage/s_lock.h

src/interfaces/libpq/libpq-int.h