Merge remote-tracking branch 'remotes/ehabkost/tags/machine-pull-request' into staging

Machine Core queue, 2016-05-20

# gpg: Signature made Fri 20 May 2016 21:26:49 BST using RSA key ID 984DC5A6
# gpg: Good signature from "Eduardo Habkost <ehabkost@redhat.com>"

* remotes/ehabkost/tags/machine-pull-request: (21 commits)
  Use &error_fatal when initializing crypto on qemu-{img,io,nbd}
  vl: Use &error_fatal when parsing monitor options
  vl: Use &error_fatal when parsing VNC options
  machine: add properties to compat_props incrementaly
  vl: Simplify global property registration
  vl: Make display_remote a local variable
  vl: Move DisplayType typedef to vl.c
  vl: Make display_type a local variable
  vl: Replace DT_NOGRAPHIC with machine option
  milkymist: Move DT_NOGRAPHIC check outside milkymist_tmu2_create()
  spice: Initialization stubs on qemu-spice.h
  gtk: Initialization stubs
  cocoa: cocoa_display_init() stub
  sdl: Initialization stubs
  curses: curses_display_init() stub
  vnc: Initialization stubs
  vl: Add DT_COCOA DisplayType value
  vl: Replace *_vga_available() functions with class_names field
  vl: Table-based select_vgahw()
  vl: Use exit(1) when requested VGA interface is unavailable
  ...

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