bpftool: Handle libbpf_probe_prog_type errors

Previously [1], we were using bpf_probe_prog_type which returned a
bool, but the new libbpf_probe_bpf_prog_type can return a negative
error code on failure. This change decides for bpftool to declare
a program type is not available on probe failure.

[1] https://lore.kernel.org/bpf/20220202225916.3313522-3-andrii@kernel.org/Signed-off-by: Milan Landaverde <milan@mdaverde.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20220331154555.422506-4-milan@mdaverde.com

tools/bpf/bpftool/feature.c

@@ -567,7 +567,7 @@ probe_prog_type(enum bpf_prog_type prog_type, bool *supported_types,
 
 		res = probe_prog_type_ifindex(prog_type, ifindex);
 	} else {
-		res = libbpf_probe_bpf_prog_type(prog_type, NULL);
+		res = libbpf_probe_bpf_prog_type(prog_type, NULL) > 0;
 	}
 
 #ifdef USE_LIBCAP