bpftool: Set program type only if it differs from the desired one

After commit d6e6286a ("libbpf: disassociate section handler on explicit
bpf_program__set_type() call"), bpf_program__set_type() will force cleanup
the program's SEC() definition, this commit fixed the test helper but missed
the bpftool, which leads to bpftool prog autoattach broken as follows:

  $ bpftool prog load spi-xfer-r1v1.o /sys/fs/bpf/test autoattach
  Program spi_xfer_r1v1 does not support autoattach, falling back to pinning

This patch fix bpftool to set program type only if it differs.

Fixes: d6e6286a ("libbpf: disassociate section handler on explicit bpf_program__set_type() call")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230407081427.2621590-1-weiyongjun@huaweicloud.com

tools/bpf/bpftool/prog.c

@@ -1685,7 +1685,8 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 		}
 
 		bpf_program__set_ifindex(pos, ifindex);
-		bpf_program__set_type(pos, prog_type);
+		if (bpf_program__type(pos) != prog_type)
+			bpf_program__set_type(pos, prog_type);
 		bpf_program__set_expected_attach_type(pos, expected_attach_type);
 	}