Both callers of ChanRead() have simlar epilogs.  Shift that into ChanRead
and refactor.
Documentation header for ChanRead()
io-34.21 - fix bugs in normally skipped test.
io-35.18b - knownBug is not buggy on this branch.
Fixup ChanRead() header.  Note (dstSize > 0) precondition.
Restore default suppression of large file test.
Convert "impossible" test to a "knownBug" test.  Exposes a segfault!
Added comment explaining the "knownBug"
Correct namespace bugs in normally skipped tests.
Constrain them as "knownBug" rather than "unknownFailure".
missing declaration
Avoid multiple returns of connect errors
Return async connect error by first following read or write operation.
Renamed function CreateClientSocket to TcpConnect and variable error to connectError
Rename CreateClientSocket to TcpConnect
Rename error to connectError in struct TcpState.
Changed error report logic, that an async connect error is only reported by 'fconfigure -error' and not by a possible last command terminating the async connect. The terminating command always returns "socket is not connected" on connect error. In addition, some flags were renamed: TCP_ASYNC_SOCKET to TCP_NONBLOCKING and also the new state flags.
Beautify check for async connect reentry
  *  Give clearer names to some of the state flags and sync them with Windos where it makes sense.
  *  Rework WaitForConnect once more to always report ENOTCONN on I/O operations on failed async sockets.
  *  Fix synchronous connections to a server that only listens on IPv6 (or whatever comes later in the list returned by getaddrinfo(), socket-15.*)
  *  Fix spurious writable event on async sockets (socket-14.15).
Possible fix for [47d66253c92197d30bff280b02e0a9e62f07cee2|47d66253c9]: "lsearch -sorted -integer" on 64bit system
Salvaged what was left of value in the dgp-read-bytes-detour branch.
Refactored much management of the BLOCKED and EOF flags into ChanRead()
then began repairing some of the logic about them.
Tests iogt-2.* now fail because they've been crafted as experiments recording
the fine detail of reflected channel driver calls, and fixing the management
of channel flags is changing that.
Rework Tcl_ReadRaw() mostly taking things out of the loop that never repeat.