Merge pull request #1136 from ewen-naos-nz/zos

z/OS UNIX System Services port
Update VS filters for socks additions.
Remove libsodium VS import props crypt32.lib dependency.
Add socks files to VS2010 builds, update VS2012/2010 filters.
Merge pull request #1137 from evoskuil/master

VS updates for socks, rem libsodium VS crypt32 dependency.
Merge pull request #1138 from ewen-naos-nz/zos

z/OS UNIX System Services port: EAGAIN, SIGPIPE