package/libssh: security bump to version 0.9.4

Fixes CVE-2020-1730: Possible DoS in client and server when handling
AES-CTR keys with OpenSSL.

Format hash file with two spaces delimiter.

Cc: Scott Fan <fancp2007@gmail.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>