Fix ClearShaderReplacement in vtkOpenGLPolyDataMapper
ClearShaderReplacement didn't work. The to-be-removed element returned by map.find() is compared with map.end(), and should be removed when they are NOT equal, instead of equal.
ClearShaderReplacement didn't work. The to-be-removed element returned by map.find() is compared with map.end(), and should be removed when they are NOT equal, instead of equal.