Cleanup: ensure space after file named in headers

Add blank lines after file references to avoid them being interpreted as
doc-strings the following declarations.

source/blender/python/intern/bpy.h

@@ -18,6 +18,7 @@ void BPy_init_modules(struct bContext *C);
 extern PyObject *bpy_package_py;
 
 /* bpy_interface_atexit.c */
+
 void BPY_atexit_register(void);
 void BPY_atexit_unregister(void);