bind-dirs: run in DisposableVM, too

Allow the user to configure bind-dirs in the dvm template and have that
configuration applied when a DisposableVM is instantiated.

Fixes QubesOS/qubes-issues#4624
Fixes QubesOS/qubes-issues#5618

vm-systemd/bind-dirs.sh

@@ -30,8 +30,8 @@ shopt -s nullglob dotglob
 source /usr/lib/qubes/init/functions
 
 prerequisite() {
-   if ! is_rwonly_persistent ; then
-      echo "No TemplateBasedVM detected. Exiting."
+   if is_fully_persistent ; then
+      echo "No TemplateBasedVM/DisposableVM detected. Exiting."
       exit 0
    fi
 }

vm-systemd/mount-dirs.sh

@@ -15,6 +15,4 @@ echo "Mounting /rw/home onto /home" >&2
 mount /home
 echo "Mounting /rw/usrlocal onto /usr/local" >&2
 mount /usr/local
-# https://github.com/QubesOS/qubes-issues/issues/1328#issuecomment-169483029
-# Do none of the following in a DispVM.
 /usr/lib/qubes/init/bind-dirs.sh