basic/bpf-program: drop obsolete comment

As far as I can see, nothing in that particular file is from the
kernel. Let's just drop the comment.

src/basic/bpf-program.h

@@ -1,10 +1,6 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 #pragma once
 
-/***
-  [Except for the stuff copy/pasted from the kernel sources, see below]
-***/
-
 #include <linux/bpf.h>
 #include <stdint.h>
 #include <sys/syscall.h>