Run in QEMU with 4 CPUs by default

Rsconscript

@@ -199,6 +199,7 @@ task "run", desc: "Run HOS in QEMU" do
     qemu-system-x86_64
     -machine q35
     -cpu max
+    -smp cpus=4
     -serial file:qemu/serial.out
     -bios #{ovmf}
     -drive file=qemu/HOS.img,format=raw