Improve pledge() and unveil() further

- Fix getpriority()
- Add AT_MINSIGSTKSZ
- Fix bugs in BPF code
- Show more stuff in printargs.com
- Write manual test for pledge.com
- pledge() now generates tinier BPF code
- Have pledge("exec") only enable execve()
- Fix pledge.com chroot setuid functionality
- Improve pledge.com unveiling of ape loader

test/libc/calls/sched_setscheduler_test.c

@@ -22,6 +22,7 @@
 #include "libc/dce.h"
 #include "libc/errno.h"
 #include "libc/intrin/kprintf.h"
+#include "libc/limits.h"
 #include "libc/runtime/runtime.h"
 #include "libc/sysv/consts/sched.h"
 #include "libc/testlib/testlib.h"
@@ -53,6 +54,10 @@ bool CanTuneRealtimeSchedulers(void) {
   }
 }
 
+TEST(sched_getscheduler, einval) {
+  ASSERT_SYS(IsLinux() ? EINVAL : ESRCH, -1, sched_getscheduler(INT_MIN));
+}
+
 TEST(sched_setscheduler, test) {
   struct sched_param p = {sched_get_priority_min(SCHED_OTHER)};
   EXPECT_SYS(0, DEFAULT_POLICY, sched_setscheduler(0, SCHED_OTHER, &p));