Removed thread debugging printf messages
Imported for bug [97069ea11a] from branch bug-97069ea11a: empty error message on stalled background flush after async socket connect fail
Marked all communication variables which are set by notifier thread with "volatile".
Make the naming of TcpState variables consistent
  *  Rework WaitForConnect() to fix synchronous completion of asynchronous connections.
  *  Let TcpInputProc() and TcpOutputProc() fail before calling any I/O syscalls when an asynchronous connection has failed.
  *  Adjust the tests accordingly.
Add tests for bugs [336441ed59] and [581937ab1e] from core-8-5-branch.
Fix/improve tests.
Move tests 8.2 and 8.3 out of the IPv4/IPv6 loop to 14.13 and 14.4.
Moved tests socket-8.2 and socket-8.3 to socket-14.3 and socket-14.4 and made them robust against connect failures