[201811][snmpagent][swss-common] advance sub module head to include o…

…verlay SNMP (#2721)

* [snmpagent][swss-common] advance sub module head to include overlay SNMP

Submodule src/sonic-snmpagent 0f2bbd7..26f0495:
  > Remove verbose feature missing logs (#102)
  > Enable overriding interface counters OIDs (#98)

Submodule src/sonic-swss-common 5f4abd9..36fd5e9:
  > Add new DB index for SNMP_OVERLAY_DB (#262)

Note: overlay DB also requires change in swss-common, which has been
      moved ahead.

Signed-off-by: Ying Xie <ying.xie@microsoft.com>

* [utilities] advance utilities sub-module head

Submodule src/sonic-utilities 9d9aaa0..d1070b2:
  > [warm-reboot] initialize warm reboot state table before warm rebooting (#492)
  > Allow config shutdown and startup operations on valid PortChannel interface names (#474)