rpcd: update to lastest HEAD

rpcd: update to lastest HEAD

All these changes are important enough to have them in the 17.01.

8206219 uci: fix memory leak in rpc_uci_replace_savedir()
10f7878 exec: close stdout and stderr streams on child signal
92d0d75 uci: use correct sort index when reordering sections
66a9bad uci: fix memory leak in rpc_uci_apply_timeout()
2423162 uci: switch to proper save directory on apply/rollback
edd37f8 uci: add rpc_uci_replace_savedir() helper
eb09f3a session: ignore non-string username attribute upon restore
3d400c7 session: support reclaiming pending apply session
f0f6f81 session: remove redundant key attribute to rpc_session_set()
6994c87 uci: fix session delta isolation

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>