Merge remote-tracking branch 'remotes/elmarco/tags/chardev-pull-request' into staging

Merge remote-tracking branch 'remotes/elmarco/tags/chardev-pull-request' into staging

Chardev fixes

# gpg: Signature made Wed 13 Feb 2019 16:18:36 GMT
# gpg:                using RSA key DAE8E10975969CE5
# gpg: Good signature from "Marc-André Lureau <marcandre.lureau@redhat.com>" [full]
# gpg:                 aka "Marc-André Lureau <marcandre.lureau@gmail.com>" [full]
# Primary key fingerprint: 87A9 BD93 3F87 C606 D276  F62D DAE8 E109 7596 9CE5

* remotes/elmarco/tags/chardev-pull-request: (25 commits)
  char-pty: remove write_lock usage
  char-pty: remove the check for connection on write
  chardev: add a note about frontend sources and context switch
  terminal3270: do not use backend timer sources
  char: update the mux handlers in class callback
  chardev/wctablet: Fix a typo
  char: allow specifying a GMainContext at opening time
  chardev: ensure termios is fully initialized
  tests: expand coverage of socket chardev test
  chardev: fix race with client connections in tcp_chr_wait_connected
  chardev: disallow TLS/telnet/websocket with tcp_chr_wait_connected
  chardev: honour the reconnect setting in tcp_chr_wait_connected
  chardev: use a state machine for socket connection state
  chardev: split up qmp_chardev_open_socket connection code
  chardev: split tcp_chr_wait_connected into two methods
  chardev: remove unused 'sioc' variable & cleanup paths
  chardev: ensure qemu_chr_parse_compat reports missing driver error
  chardev: remove many local variables in qemu_chr_parse_socket
  chardev: forbid 'wait' option with client sockets
  chardev: forbid 'reconnect' option with server sockets
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>