Related: #2958
Motivation:
SslHandler currently does not issue a read() request when it is
handshaking. It makes a connection with autoRead off stall, because a
user's read() request can be used to read the handshake response which
is invisible to the user.
Modifications:
- SslHandler now issues a read() request when:
- the current handshake is in progress and channelReadComplete() is
invoked
- the current handshake is complete and a user issued a read() request
during handshake
- Rename flushedBeforeHandshakeDone to flushedBeforeHandshake for
consistency with the new variable 'readDuringHandshake'
Result:
SslHandler should work regardless whether autoRead is on or off.