Add a "fork" of musl as //fusl.

fusl/src/sched/affinity.c

+#define _GNU_SOURCE
+#include <sched.h>
+#include <string.h>
+#include "pthread_impl.h"
+#include "syscall.h"
+
+int sched_setaffinity(pid_t tid, size_t size, const cpu_set_t *set)
+{
+        return syscall(SYS_sched_setaffinity, tid, size, set);
+}
+
+int pthread_setaffinity_np(pthread_t td, size_t size, const cpu_set_t *set)
+{
+        return -__syscall(SYS_sched_setaffinity, td->tid, size, set);
+}
+
+static int do_getaffinity(pid_t tid, size_t size, cpu_set_t *set)
+{
+        long ret = __syscall(SYS_sched_getaffinity, tid, size, set);
+        if (ret < 0) return ret;
+        if (ret < size) memset((char *)set+ret, 0, size-ret);
+        return 0;
+}
+
+int sched_getaffinity(pid_t tid, size_t size, cpu_set_t *set)
+{
+        return __syscall_ret(do_getaffinity(tid, size, set));
+}
+
+int pthread_getaffinity_np(pthread_t td, size_t size, cpu_set_t *set)
+{
+        return -do_getaffinity(td->tid, size, set);
+}