Cleanup: PyMethodDef formatting

Missed these changes in [0].

Also replace designated initializers in some C code, as it's not used
often and would need to be removed when converting to C++.

[0] e555ede626

source/blender/python/gpu/gpu_py_matrix.c

@@ -528,9 +528,14 @@ static struct PyMethodDef pygpu_matrix__tp_methods[] = {
 PyDoc_STRVAR(pygpu_matrix__tp_doc, "This module provides access to the matrix stack.");
 static PyModuleDef pygpu_matrix_module_def = {
     PyModuleDef_HEAD_INIT,
-    .m_name = "gpu.matrix",
-    .m_doc = pygpu_matrix__tp_doc,
-    .m_methods = pygpu_matrix__tp_methods,
+    /*m_name*/ "gpu.matrix",
+    /*m_doc*/ pygpu_matrix__tp_doc,
+    /*m_size*/ 0,
+    /*m_methods*/ pygpu_matrix__tp_methods,
+    /*m_slots*/ NULL,
+    /*m_traverse*/ NULL,
+    /*m_clear*/ NULL,
+    /*m_free*/ NULL,
 };
 
 PyObject *bpygpu_matrix_init(void)