tools/bpftool: Relicense bpftool's BPF profiler prog as dual-license GPL/BSD

Relicense it to be compatible with the rest of bpftool files.
Suggested-by: NQuentin Monnet <quentin@isovalent.com>
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200619222024.519774-1-andriin@fb.com

tools/bpf/bpftool/skeleton/profiler.bpf.c

-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 // Copyright (c) 2020 Facebook
 #include "profiler.h"
 #include <linux/bpf.h>
@@ -116,4 +116,4 @@ int BPF_PROG(fexit_XXX)
 	return 0;
 }
 
-char LICENSE[] SEC("license") = "GPL";
+char LICENSE[] SEC("license") = "Dual BSD/GPL";