The result of folding a ternary operator may be a TIntermSymbol node
where the qualifier doesn't match the qualifier of the variable that
the node is referring to.

Get the qualifier from the variable instead of directly from
TIntermSymbol when collecting variables in CollectVariables or when
tracking referenced variables in OutputHLSL.

BUG=angleproject:2288
TEST=angle_unittests, angle_end2end_tests

Change-Id: If294a7fe9dca50f2ebcea3feff887e72a521d395
Reviewed-on: https://chromium-review.googlesource.com/836893Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>