gallium: for TEST_DRAW_PASSTHROUGH, pass inClipCoords=FALSE to st_draw_vertices()

When pass-through mode is fully supported we'll clean this up more.

src/mesa/state_tracker/st_cb_clear.c

@@ -259,7 +259,13 @@ draw_quad(GLcontext *ctx,
       verts[i][1][3] = color[3];
    }
 
-   st_draw_vertices(ctx, PIPE_PRIM_QUADS, 4, (float *) verts, 2, GL_FALSE);
+   st_draw_vertices(ctx, PIPE_PRIM_POLYGON, 4, (float *) verts, 2,
+#if TEST_DRAW_PASSTHROUGH
+                    GL_TRUE
+#else
+                    GL_FALSE
+#endif
+                    );
 }