Revert "[master] Merge branch 'trac4106'"
This reverts commit 8f2a1f8a, reversing changes made to ed7edadc. This merge introduced regressions in our build farm and revealed issues in the DHCP4o6 IPC code. It also revealed some differences in sockets handling under Linux and BSD. Rather than continue patching this here, we should work on the branch to resolve all issues and then merge 1.1.