scheduler: implement nice

kernel-src/sys/syscalls/nice.c

@@ -0,0 +1,17 @@
+#include <kernel/syscalls.h>
+#include <kernel/thread.h>
+#include <arch/cpu.h>
+
+syscallret_t syscall_nice(context_t *, int nice) {
+	syscallret_t ret;
+
+
+	if (nice < 0) {
+		
+	}
+
+	current_thread()->proc->nice = max(min(current_thread()->proc->nice + nice, SCHED_NICE_MAX), SCHED_NICE_MIN);
+
+	ret.ret = current_thread()->proc->nice;
+	return ret;
+}