Apply swapstate file exists check to Squid3

Issue reported in forum https://forum.pfsense.org/index.php?topic=78733.msg
This extra check was applied to Squid2 back in 2013.
Apply swapstate file exists check to Squid3

Issue reported in forum https://forum.pfsense.org/index.php?topic=78733.msg
This extra check was applied to Squid2 back in 2013.
Bump squid3 and squid-dev for swapstate code change
Bump squid3 and squid-dev for swapstate code change
Bump squid3 and squid-dev for swapstate code change
Bump squid3-dev again

The version in pkg_config.10 was already ahead, make this consistent.
Bump squid3-dev again

The version in pkg_config.10 was already ahead, make this consistent.
Merge pull request #724 from phil-davis/patch-1