feat: added reaper and suicide support

kernel/libk/syscall.c

@@ -35,3 +35,7 @@ void syscall_yield_irq(uint16_t irq) {
 void syscall_job_suspend() {
     syscall1(SYSCALL_SUSPEND);
 }
+
+void syscall_kill_self() {
+    syscall1(SYSCALL_KILL_SELF);
+}