Password hashing unit tests are too slow
The scrypt and pbkdf2 and pwbox tests I added for legacy/trac#12981 (moved) seem to run a bit slow. Running slow is kind of the point of a password hashing scheme, but slow unit tests are anathema.
We could make these tests (or the slower versions of them) off-by-default using the TT_OFF_BY_DEFAULT flag, I guess. But is that wise?