create /sysroot directory in initrd, guestfsd relies on it

OBS-URL: https://build.opensuse.org/package/show/Virtualization/libguestfs?expand=0&rev=61

libguestfs.mkinitrd.setup.sh

@@ -2,6 +2,10 @@
 #%stage: block
 #
 
+# many guestfish commands need a mount point
+# in guestfsd the mount point defaults to /sysroot
+mkdir -vp $tmp_mnt/sysroot
+
 for f in /etc/magic /usr/share/misc/magic*
 do
 	if test -e $f