fix(clippy): make clippy = host libs + riscv programs (shared PROGRAMS); libkos alloc spinlock (was unlocked across threads); keystore Account; gpu Rect; factory Entry; Default impls, let-chains, div_ceil, iter loops

crates/libkos/src/syscall/process.rs

@@ -12,12 +12,17 @@ use types::time::Ticks;
 
 pub fn exit() -> ! {
     let _ = call0(SYS_EXIT);
-    loop {}
+    // The kernel does not return from an exit.
+    loop {
+        core::hint::spin_loop();
+    }
 }
 
 pub fn exit_thread() -> ! {
     let _ = call0(SYS_EXIT_THREAD);
-    loop {}
+    loop {
+        core::hint::spin_loop();
+    }
 }
 
 pub fn yield_now() {
@@ -28,7 +33,9 @@ pub fn yield_now() {
 /// call fails and this spins, since there is nothing sensible to return.
 pub fn halt(control: CapSlot) -> ! {
     let _ = raw(SYS_HALT, [control.value() as usize, 0, 0, 0, 0, 0]);
-    loop {}
+    loop {
+        yield_now();
+    }
 }
 
 pub fn get_time() -> Ticks {