vga: add ramfb, print virglrenderer version

# gpg: Signature made Mon 18 Jun 2018 10:57:38 BST
# gpg:                using RSA key 4CB6D8EED3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"
# Primary key fingerprint: A032 8CFF B93A 17A7 9901  FE7D 4CB6 D8EE D3E8 7138

* remotes/kraxel/tags/vga-20180618-pull-request:
  Add ramfb MAINTAINERS entry
  hw/display: add standalone ramfb device
  hw/display: add ramfb, a simple boot framebuffer living in guest ram
  configure: print virglrenderer version

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