libbpf: Use elfgetshdrnum() instead of eshnum
This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v6.0.16 by commit 854f8c61422053f71e3cf0c4abf757c8aa5c748d, it was introduced in version v5.17 by commit 0d6988e16a12ebd41d3e268992211b0ceba44ed7. For more details please see the references link.