Turn off multisamples so antialiasing doesn't cause test failures.

TestSplitViewportStereoHorizontal is failing on several platforms.

Some linux platforms failed because their graphics cards don't do
antialiasing.  This commit turns of antialiasing on ALL platforms
provides a new non-antialiased baseline, and increases the error
threshold.

All windows machines failed because SetStereoRender was called
before the StereoType was set.  This commit should fix that, because
it calls SetStereoType before SetStereoRender.

All OS X machines still fail because the ViewAngle is, for some
unknown reason, not interpreted properly for this test on that
platform.

Change-Id: Ic159af6f4350fcaa0b3cea7f645d4062030f00ee
Merge topic 'splitviewport-stereo-multisample' into master

047da12d Turn off multisamples so antialiasing doesn't cause test failures.