bpftool: Fix memory leak in do_build_table_cb

strdup() allocates memory for path. We need to release the memory in the
following error path. Add free() to avoid memory leak.

Fixes: 8f184732b6 ("bpftool: Switch to libbpf's hashmap for pinned paths of BPF objects")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221206071906.806384-1-linmq006@gmail.com

tools/bpf/bpftool/common.c

@@ -501,6 +501,7 @@ static int do_build_table_cb(const char *fpath, const struct stat *sb,
 	if (err) {
 		p_err("failed to append entry to hashmap for ID %u, path '%s': %s",
 		      pinned_info.id, path, strerror(errno));
+		free(path);
 		goto out_close;
 	}