Add tests of multi-bind GL functions that take NULL arrays

util/test/demos/gl/gl_parameter_zoo.cpp

@@ -122,6 +122,9 @@ void main()
       return 5;
     }
 
+    GLuint trashvao = MakeVAO();
+    glBindVertexArray(trashvao);
+
     GLuint vao = MakeVAO();
     glBindVertexArray(vao);
 
@@ -196,6 +199,14 @@ void main()
 
       glBindBuffersBase(GL_SHADER_STORAGE_BUFFER, 0, 4, NULL);
 
+      glBindVertexArray(trashvao);
+      glBindVertexBuffers(0, 4, NULL, NULL, NULL);
+      glBindTextures(0, 10, NULL);
+      glBindSamplers(0, 10, NULL);
+      glBindImageTextures(0, 4, NULL);
+
+      glBindVertexArray(vao);
+
       float col[] = {1.0f, 0.0f, 1.0f, 1.0f};
       glClearBufferfv(GL_COLOR, 0, col);