Merge topic 'fix-opengl-render-window-debug-builds'

8d73768a OpenGL2: Use #ifdef instead of #if to fix compiler error

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Reviewed-by: Ben Boeckel <ben.boeckel@kitware.com>
Reviewed-by: Mathieu Westphal (Kitware) <mathieu.westphal@kitware.com>
Merge-request: !10664