SIGILL (possibly OOM) on 32-bit linux build machine

[bkoropoff]

Logs: http://buildbot.rust-lang.org/builders/auto-linux-32-nopt-t/builds/2161/steps/test/logs/stdio

Occurred on PR #18730, which was too trivial a change to have been the cause

[bkoropoff]

#18483 also had a similar problem on the same machine.

Logs: http://buildbot.rust-lang.org/builders/auto-linux-32-nopt-c/builds/2141/steps/compile/logs/stdio

[eddyb]

#18483 didn't change codegen, but I was worried it was responsible somehow.

I didn't realize the abort could have been OOM, but that makes sense in retrospective.
This calls for a quick resolution of #18678.

[thestinger]

Closing in favour of #18784.