The sample program aescrypt2 shows bad practice: hand-rolled CBC
implementation, CBC+HMAC for AEAD, hand-rolled iterated SHA-2 for key
stretching, no algorithm agility. The new sample program pbcrypt does
the same thing, but better. So remove aescrypt2.
Fix#1906
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>