Add a new kind of db enc./pbkdf test type to cmd_export.sh

(cherry picked from commit b5ac5625ab14e34d66723905d925716ed005d586)
bcrypt/sha2.c: sync. with upstream r1.14 - r1.16

Also, instead of swap32()/swap64(), use Linux specific functions for
byte swapping (e.g.: htobe64() and friends).

(cherry picked from commit e69fb498acdbfd079ff74f415369ab24d2f984de)