Updating qemu to 2.9 results in a strange VMTest fail:
2017/08/15 15:24:52 - au_worker.py - INFO    : SimpleTestVerify: Running smoke suite to verify image.
INFO    : QEMU binary: /b/c/cbuild/repository/chroot/usr/bin/qemu-system-x86_64
/b/c/cbuild/repository/chroot/usr/bin/qemu-system-x86_64: error while loading shared libraries: libtinfow.so.5: cannot open shared object file: No such file or directory

https://luci-milo.appspot.com/buildbot/chromiumos.tryserver/pre_cq/50025

iirc, upstream has messed around with the static settings on the binaries, and i haven't gotten around to fixing it.  so you end up with non-static qemu-system programs and they don't work outside of the chroot.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/1f2e65cfabebf11ec2bb508d224d5f78a9310a2c

commit 1f2e65cfabebf11ec2bb508d224d5f78a9310a2c
Author: Manoj Gupta <manojgupta@google.com>
Date: Wed Sep 06 23:54:34 2017

qemu: Force use of libstdc++ with clang.

qemu 2.6.0 can't be build using libc++. Force it to
be built using libstdc++ for now.

This is a no-op change since libstdc++ is currently the default in clang.

BUG= chromium:747613 
TEST=qemu builds even when libc++ is set as default in clang.

Change-Id: Ibfbb3e631284ade53b75835bab66f481b4bab268
Reviewed-on: https://chromium-review.googlesource.com/651567
Commit-Ready: Manoj Gupta <manojgupta@chromium.org>
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

[add] https://crrev.com/1f2e65cfabebf11ec2bb508d224d5f78a9310a2c/chromeos/config/env/app-emulation/qemu

Builds after forcing libstdc++. Don't want to try upgrading qemu right now based on #3.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/b36fb4dbb28dbac4f4eb644a40274a73a2c0961f

commit b36fb4dbb28dbac4f4eb644a40274a73a2c0961f
Author: chrome-bot <chrome-bot@chromium.org>
Date: Wed Oct 17 21:23:18 2018

qemu: upgraded package to unstable upstream

Moved qemu back in to portage-stable and added necessary dependencies
to default/linux/package.use

BUG= 884947 ,  803281 ,  747613 
TEST="sudo emerge qemu", "emerge-grunt chromeos-fonts", buildbot VM tests succeed
CQ-DEPEND=CL:1249722

Change-Id: I8ffe8c8c5454f49720c9b8fe236ca26ecf64cd15
Reviewed-on: https://chromium-review.googlesource.com/1249603
Commit-Ready: Chris McDonald <cjmcdonald@chromium.org>
Tested-by: Drans Sulaiman <drans4775@gmail.com>
Tested-by: Chris McDonald <cjmcdonald@chromium.org>
Reviewed-by: Drans Sulaiman <drans4775@gmail.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/files/qemu-2.5.0-cflags.patch
[modify] https://crrev.com/b36fb4dbb28dbac4f4eb644a40274a73a2c0961f/profiles/default/linux/package.use
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/files/qemu-2.5.0-sysmacros.patch
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/files/qemu-2.6.0-slirp-send-queue-hangs.patch
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/metadata.xml
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/files/qemu-2.6.0-o_tmpfile.patch
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/qemu-2.6.0.ebuild
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/files/65-kvm.rules
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/files/qemu-2.6.0-ucontext.patch
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/files/bridge.conf
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/files/qemu-binfmt.initd-r1
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/files/qemu-2.6.0-memfd.patch
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/qemu-2.6.0-r4.ebuild
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/Manifest
[delete] https://crrev.com/b5f2b54349ff6529aaeb267e7302fee232436300/app-emulation/qemu/files/qemu-2.6.0-crypto-static.patch

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/portage-stable/+/8418f6d332b215968eefe8919a696b4e59fd7333

commit 8418f6d332b215968eefe8919a696b4e59fd7333
Author: Manoj Gupta <manojgupta@google.com>
Date: Sat Dec 01 13:19:27 2018

qemu: Rev bump.

Revbump qemu to force a rebuild.
This will make qemu build with libc++ instead of libstc++.

BUG= chromium:747613 
TEST=pre-cq

CQ-DEPEND=CL:1357120

Change-Id: Ibaf56d4d648bb757b82c381bc09cc09ebd5ee33d
Reviewed-on: https://chromium-review.googlesource.com/1356900
Commit-Ready: Manoj Gupta <manojgupta@chromium.org>
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Luis Lozano <llozano@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

[add] https://crrev.com/8418f6d332b215968eefe8919a696b4e59fd7333/app-emulation/qemu/qemu-3.0.0-r1.ebuild

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/2838ff3b8fab0b59a2c40f0e614367f71c4d8065

commit 2838ff3b8fab0b59a2c40f0e614367f71c4d8065
Author: Manoj Gupta <manojgupta@google.com>
Date: Sat Dec 01 13:19:27 2018

qemu: Stop forced build with libstdc++.

qemu 3.0.0 can be built with libc++.

BUG= chromium:747613 
TEST=pre-cq

CQ-DEPEND=CL:1356900

Change-Id: Iff5d7b72fffc2c8411c812dab0c4903b3ea00d63
Reviewed-on: https://chromium-review.googlesource.com/1357120
Commit-Ready: Manoj Gupta <manojgupta@chromium.org>
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Luis Lozano <llozano@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

[delete] https://crrev.com/a5d62df6196c7b97545a2f6e42f9bfa91597430f/chromeos/config/env/app-emulation/qemu

Changing status from won't fix to verified.