[feature/passwords] Make sure hash has the required length

Also added tests to make sure that crypto drivers are enforcing the hash
length.

PHPBB3-11610

phpBB/includes/crypto/driver/bcrypt.php

@@ -53,6 +53,10 @@ class phpbb_crypto_driver_bcrypt extends phpbb_crypto_driver_base
 		}
 
 		$hash = crypt($password, $salt);
+		if (strlen($hash) < 60)
+		{
+			return false;
+		}
 		return $hash;
 	}