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 patches

# gpg: Signature made Wed 03 Oct 2018 11:57:34 BST
# gpg:                using RSA key DAE8E10975969CE5
# gpg: Good signature from "Marc-André Lureau <marcandre.lureau@redhat.com>"
# gpg:                 aka "Marc-André Lureau <marcandre.lureau@gmail.com>"
# Primary key fingerprint: 87A9 BD93 3F87 C606 D276  F62D DAE8 E109 7596 9CE5

* remotes/elmarco/tags/chardev-pull-request:
  chardev: use a child source for qio input source
  chardev: mark the calls that allow an implicit mux monitor
  char.h: fix gtk-doc comment style
  chardev: unref if underlying chardev has no parent
  chardev: remove qemu_chr_fe_read_all() counter
  chardev: avoid crash if no associated address

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