libbpf: Fix warning in calloc() usage

When compiling libbpf with some compilers, this warning is triggered:

libbpf.c: In function ‘bpf_object__gen_loader’:
libbpf.c:9209:28: error: ‘calloc’ sizes specified with ‘sizeof’ in the earlier argument and not in the later argument [-Werror=calloc-transposed-args]
9209 | gen = calloc(sizeof(*gen), 1);
| ^
libbpf.c:9209:28: note: earlier argument should specify number of elements, later size of each element

Fix this by inverting the calloc() arguments.

Signed-off-by: Matteo Croce <[e-mail]>
Signed-off-by: Andrii Nakryiko <[e-mail]>
Acked-by: Yonghong Song <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/lib/bpf/libbpf.c

···
 		return libbpf_err(-EFAULT);
 	if (!OPTS_VALID(opts, gen_loader_opts))
 		return libbpf_err(-EINVAL);
-	gen = calloc(sizeof(*gen), 1);
+	gen = calloc(1, sizeof(*gen));
 	if (!gen)
 		return libbpf_err(-ENOMEM);
 	gen->opts = opts;