BPY: move bpy and mathutils to C++

Also see #103343.

Pull Request: https://projects.blender.org/blender/blender/pulls/110299

source/blender/python/gpu/gpu_py_api.h

@@ -8,8 +8,16 @@
 
 #pragma once
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* Each type object could have a method for free GPU resources.
  * However, it is currently of little use. */
 // #define BPYGPU_USE_GPUOBJ_FREE_METHOD
 
 PyObject *BPyInit_gpu(void);
+
+#ifdef __cplusplus
+}
+#endif