Explicitly stop reading before closing the nmtcpsocket

Explicitly stop reading before closing the nmtcpsocket

When closing the socket that is actively reading from the stream, the
read_cb() could be called between uv_close() and close callback when the
server socket has been already detached hence using sock->statichandle
after it has been already freed.

(cherry picked from commit 97b33e5bde296feb82c1d8bb703e56c1b224e129)