Unfortunately, different runtime libraries and/or compilers differ on
whether a class without any copy constructor, move constructor, copy
assignment and move assignment operator is considered trivially
copyable.
See discussion on https://crrev.com/c/941521.

This CL adds a comment about this, and deletes a test for this specific
case.

R=mstarzinger@chromium.org
CC=jyan@ca.ibm.com, ivica.bogosavljevic@mips.com

Change-Id: Ie07adda370e5e955b782e72356b50121477d4623
Reviewed-on: https://chromium-review.googlesource.com/944081
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51704}