Merge remote-tracking branch 'remotes/dgilbert/tags/pull-hmp-20180621' into staging

HMP pull 2018-06-21

Minor fixes and reenable preconfig

# gpg: Signature made Thu 21 Jun 2018 17:43:09 BST
# gpg:                using RSA key 0516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>"
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert/tags/pull-hmp-20180621:
  hmp: Allow HMP in preconfig state again
  hmp: add exit_preconfig
  hmp: Add commands for preconfig
  qmp: Enable a few commands in preconfig state
  hmp: Restrict auto-complete in preconfig
  hmp: Allow help on preconfig commands
  hmp: Add flag for preconfig commands
  hmp-commands: use long for begin and length in dump-guest-memory
  monitor: report entirety of hmp command on error

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