[libc] Implement CPU_{AND,OR,XOR,EQUAL}(_S)? macros (#205412)
This patch implements CPU_AND, CPU_OR, CPU_XOR, and CPU_EQUAL macros
(along with their _S variants) from sched.h.
The implementation follows existing patterns by adding internal entry
points (__sched_andcpuset, __sched_orcpuset, __sched_xorcpuset, and
__sched_cpuequal) that perform bitwise operations on cpu_set_t. For
__sched_cpuequal, I use inline_memcmp instead of a manual loop.
Assisted by Gemini.