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
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.
merge 8.5
Push the setting and clearing of CHANNEL_BLOCKED flag to the more inner
parts of the channel read machinery.
merge 8.5
Move the resets and testings of the BLOCKED flag to where they make more sense.
Improved use of EOF state to avoid worthless allocations.
Repair broken tests iogt-2.[123].
What happened is that now that EOF flags no loger leak acros channel
stack layers, an EOF in the bottom channel isn't detected in the top one
until the ChanRead call at the top level actually returns 0 bytes.  This
causes one more query/ma
Simplify the inputProc of [testchannel transform].
Rework the management of the CHANNEL_BLOCKED and CHANNEL_EOF flags, in
particular not allowing them to leak between multiple layers of a stacked
channel.  Much common code refactored into ChanRead().