qemu: security bump to version 2.8.1.1

Fixes the following security issues and adds a number of other bigfixes:

2.8.1: Changelog:
https://lists.gnu.org/archive/html/qemu-devel/2017-03/msg06332.html

CVE-2017-2615 - display: cirrus: oob access while doing bitblt copy backward
mode

CVE-2017-2620 - display: cirrus: out-of-bounds access issue while in
cirrus_bitblt_cputovideo

CVE-2017-2630 - nbd: oob stack write in client routine drop_sync

2.8.1.1 Changelog:
https://lists.gnu.org/archive/html/qemu-devel/2017-04/msg03460.html

CVE-2017-7471 - 9p: virtfs allows guest to change filesystem attributes on
host

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit af0f2d2bbcaca9000e62b5388f4c3cd8e700c6ff)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/qemu/qemu.hash

@@ -1,2 +1,2 @@
 # Locally computed, tarball verified with GPG signature
-sha256 dafd5d7f649907b6b617b822692f4c82e60cf29bc0fc58bc2036219b591e5e62  qemu-2.8.0.tar.bz2
+sha256 f62ab18a1fb9ff5b4c81ed44becc945b11581eff777618141bdb787da55d3638  qemu-2.8.1.1.tar.bz2

package/qemu/qemu.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-QEMU_VERSION = 2.8.0
+QEMU_VERSION = 2.8.1.1
 QEMU_SOURCE = qemu-$(QEMU_VERSION).tar.bz2
 QEMU_SITE = http://wiki.qemu.org/download
 QEMU_LICENSE = GPLv2, LGPLv2.1, MIT, BSD-3c, BSD-2c, Others/BSD-1c