hst: expose scheduling policy

This is primarily useful for poorly written music players for now.

Signed-off-by: Ophestra <cat@gensokyo.uk>

test/test.py

@@ -206,6 +206,14 @@ machine.wait_until_fails("pgrep foot", timeout=5)
 machine.wait_for_file("/tmp/shim-cont-unexpected-pid")
 print(machine.succeed('grep "shim: got SIGCONT from unexpected process$" /tmp/shim-cont-unexpected-pid'))
 
+# Check setscheduler:
+sched_unset = int(machine.succeed("sudo -u alice -i hakurei -v run cat /proc/self/sched | grep '^policy' | tr -d ' ' | cut -d ':' -f 2"))
+if sched_unset != 0:
+    raise Exception(f"unexpected unset policy: {sched_unset}")
+sched_idle = int(machine.succeed("sudo -u alice -i hakurei -v run --sched=idle cat /proc/self/sched | grep '^policy' | tr -d ' ' | cut -d ':' -f 2"))
+if sched_idle != 5:
+    raise Exception(f"unexpected idle policy: {sched_idle}")
+
 # Start app (foot) with Wayland enablement:
 swaymsg("exec ne-foot")
 wait_for_window(f"u0_a{hakurei_identity(0)}@machine")