Use nullptr consistently in TIntermConstantUnion::fold Newly added code in TIntermConstantUnion::fold uses nullptr where as remaining part of the function uses NULL. This change removes NULL and consistently uses nullptr in complete function. Change-Id: I600dcf11b686d8d72b2bcdac88b7158288c68105 Reviewed-on: https://chromium-review.googlesource.com/265395 Reviewed-by: Olli Etuaho <oetuaho@nvidia.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Olli Etuaho <oetuaho@nvidia.com>