qemu: 9p host guest directory sharing

build

@@ -110,6 +110,7 @@ fi
 
 cd "${root_dir}/kernel_module"
 ./make-host.sh -j "$j" clean
+mkdir -p 9p
 cd "${buildroot_dir}"
 # HOST_QEMU_OPTS is a hack that happens to work because the QEMU package luckly uses += at all times.
 # It shouldn't be necessary in the first place: https://bugs.busybox.net/show_bug.cgi?id=9936