perf bench futex: Fix memory leak of perfcpumap__new()
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 v5.15.5 by commit 99643bdc6ff1c75ccd2871368fbcd20e8231d77e, it was introduced in version v5.4 by commit 9c3516d1b850ea938b074df33e4c86d721c77720. For more details please see the references link.