Add $GUEST_TWEAKS variable to allow for guest_os specific tweaks

quickemu

@@ -91,6 +91,7 @@ function vm_boot() {
   local VMDIR=$(dirname ${disk_img})
   local BIOS=""
   local CPU="-cpu host,kvm=on"
+  local GUEST_TWEAKS=""
   local VIDEO_DRV=""
   local GL="on"
   local VIRGL="on"
@@ -125,6 +126,7 @@ function vm_boot() {
       ;;
     windows)
       CPU="${CPU},hv_time"
+      GUEST_TWEAKS="-no-hpet"
       VIDEO_DRV="qxl"
       ;;
     *)
@@ -265,7 +267,7 @@ function vm_boot() {
 
   # Boot the iso image
   ${QEMU} -name ${VMNAME},process=${VMNAME} \
-    ${BIOS} \
+    ${BIOS} ${GUEST_TWEAKS} \
     -drive id=disk,file=${disk_img},format=qcow2,if=virtio,aio=native,cache.direct=on \
     ${ISO_BOOT} ${ISO_DRIVER} \
     -enable-kvm \