Cleanup: avoid shadowing, redundant assignment & minor changes

Quiet cppecheck warnings, use const pointers, ELEM(..) macro,
replace NULL -> nullptr, unsigned int -> uint.

source/blender/python/gpu/gpu_py.cc

@@ -53,7 +53,7 @@ PyC_StringEnumItems bpygpu_dataformat_items[] = {
 /** \name Utilities
  * \{ */
 
-bool bpygpu_is_init_or_error(void)
+bool bpygpu_is_init_or_error()
 {
   if (!GPU_is_init()) {
     PyErr_SetString(PyExc_SystemError,

source/blender/python/intern/bpy_app_translations.cc

@@ -634,7 +634,7 @@ static PyObject *app_translations_pgettext_n(BlenderAppTranslations * /*self*/,
                                              PyObject *args,
                                              PyObject *kw)
 {
-  static const char *kwlist[] = {"msgid", "msgctxt", NULL};
+  static const char *kwlist[] = {"msgid", "msgctxt", nullptr};
   PyObject *msgid, *msgctxt;
   // (void)_pgettext;