Fix function declaration of some modifiers

Those functions did not use evaluation context.

Also fixed lots of unused variables warnings caused by commented out code which
needs to be ported away from DerivedMesh and to evaluation context.

source/blender/python/intern/gpu_offscreen.c

@@ -147,7 +147,7 @@ static PyObject *pygpu_offscreen_unbind(BPy_GPUOffScreen *self, PyObject *args,
 /**
  * Use with PyArg_ParseTuple's "O&" formatting.
  */
-static int pygpu_offscreen_check_matrix(PyObject *o, void *p)
+static int UNUSED_FUNCTION(pygpu_offscreen_check_matrix)(PyObject *o, void *p)
 {
 	MatrixObject **pymat_p = p;
 	MatrixObject  *pymat = (MatrixObject *)o;
@@ -246,6 +246,8 @@ static PyObject *pygpu_offscreen_draw_view3d(BPy_GPUOffScreen *self, PyObject *a
 	MEM_freeN(rv3d_mats);
 
 	Py_RETURN_NONE;
+#else
+	UNUSED_VARS(self, args, kwds);
 #endif
 	return NULL;
 }