Handle inactive structure type varyings correctly Correctly handle inactive varyings of structure type when collecting transform feedback varyings. Previously, all varyings of structure type were marked as active by mistake. Bug: angleproject:5557 Test: TransformFeedbackTest.InactiveStructureVarying* Change-Id: Ica1cbce5c551cdbb97999eeac59d09a961937615 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2770680 Commit-Queue: Mohan Maiya <m.maiya@samsung.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>