libbpf: Clean gen_loader's attach kind.

mainline inclusion
from mainline-5.17-rc1
commit 19250f5f
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=19250f5fc0c283892a61f3abf9d65e6325f63897

-------------------------------------------------

The gen_loader has to clear attach_kind otherwise the programs
without attach_btf_id will fail load if they follow programs
with attach_btf_id.

Fixes: 67234743 ("libbpf: Generate loader program out of BPF ELF file.")
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Acked-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-12-alexei.starovoitov@gmail.com
(cherry picked from commit 19250f5f)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

Conflicts:
	tools/lib/bpf/gen_loader.c
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

tools/lib/bpf/gen_loader.c

@@ -1029,9 +1029,11 @@ void bpf_gen__prog_load(struct bpf_gen *gen,
 	debug_ret(gen, "prog_load %s insn_cnt %d", attr.prog_name, attr.insn_cnt);
 	/* successful or not, close btf module FDs used in extern ksyms and attach_btf_obj_fd */
 	cleanup_relos(gen, insns);
-	if (gen->attach_kind)
+	if (gen->attach_kind) {
 		emit_sys_close_blob(gen,
 				    attr_field(prog_load_attr, attach_btf_obj_fd));
+		gen->attach_kind = 0;
+	}
 	emit_check_err(gen);
 	/* remember prog_fd in the stack, if successful */
 	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_7,