Upstream commit: f2c8f6dc32
This make sit possible to store informations about a session and reuse
it later. When used by a server it increases the time to create a new
TLS session from about 1 second to less than 0.1 seconds.
The size of the ipkg file increased by about 800 Bytes.
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>