examples/vm_power_manager fails to build with gcc14 on openSUSE Tubmleweed
aarch64.

Compiler version:
    gcc (SUSE Linux) 14.2.0

Build error:
    ../examples/vm_power_manager/guest_cli/vm_power_cli_guest.c: In function
‘cmd_query_freq_list_parsed’:
    ../examples/vm_power_manager/guest_cli/vm_power_cli_guest.c:207:42: error:
implicit declaration of function ‘strtol’; did you mean ‘strtok’?
[-Wimplicit-function-declaration]
    207 |                 lcore_id = (unsigned int)strtol(res->cpu_num, &ep,
10);
        |                                          ^~~~~~
        |                                          strtok

Adding the missing stdlib.h header fixes the problem.