sandbox/linux/bpf_dsl: eliminate implicit dependency on C++ compiler behavior

sandbox/linux/bpf_dsl: eliminate implicit dependency on C++ compiler behavior

For the expression F(G(), H()), C++ does not guarantee whether G() or
H() will be evaluated first.  Apparently the system compiler on Chrome
OS makes a different decision than on Ubuntu, which causes the golden
file tests introduced by https://crrev.com/1306723002 (which were
generated on Ubuntu) to fail on Chrome OS.

Easy fix: rewrite the expression as

    g = G()
    h = H()
    F(g, h)

to avoid any compiler behavior dependency.

BUG=529480
Committed: https://crrev.com/50d2354a72b13ce2aed09af1879d37110c1454f5
Cr-Commit-Position: refs/heads/master@{#347838}

[mdempsky, 2015-09-08 22:56:35]

mdempsky@chromium.org changed reviewers:
+ jorgelo@chromium.org, rickyz@chromium.org

[mdempsky, 2015-09-08 22:56:35]

I think this should fix the Chrome OS PFQ.

[Jorge Lucangeli Obes, 2015-09-08 23:01:27]

Makes sense to me.

lgtm

[mdempsky, 2015-09-08 23:05:09]

The CQ bit was checked by mdempsky@chromium.org

[commit-bot: I haz the power, 2015-09-08 23:05:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1327693005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1327693005/1

[mdempsky, 2015-09-08 23:46:58]

The CQ bit was checked by mdempsky@chromium.org

[mdempsky, 2015-09-08 23:46:58]

The patchset sent to the CQ was uploaded after l-g-t-m from jorgelo@chromium.org
Link to the patchset: https://codereview.chromium.org/1327693005/#ps10002
(title: "Add explanatory comment per offline feedback from jln")

[commit-bot: I haz the power, 2015-09-08 23:47:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1327693005/10002
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1327693005/10002

[commit-bot: I haz the power, 2015-09-08 23:53:35]

Committed patchset #2 (id:10002)

[commit-bot: I haz the power, 2015-09-08 23:54:14]

Patchset 2 (id:??) landed as
https://crrev.com/50d2354a72b13ce2aed09af1879d37110c1454f5
Cr-Commit-Position: refs/heads/master@{#347838}