fix(virtiofs): ismounted has a dependency on the base module

When dracut.sh is called with "--modules virtiofs", make sure
dracut-lib.sh is installed by making the base module a dependency.

Author: LaszloGombos

modules.d/95virtiofs/module-setup.sh

@@ -16,7 +16,7 @@ check() {
 
 # called by dracut
 depends() {
-    return 0
+    echo base
 }
 
 # called by dracut

modules.d/95virtiofs/mount-virtiofs.sh

@@ -1,5 +1,7 @@
 #!/usr/bin/sh
 
+type ismounted > /dev/null 2>&1 || . /lib/dracut-lib.sh
+
 if [ "${fstype}" = "virtiofs" -o "${root%%:*}" = "virtiofs" ]; then
     if ! { modprobe virtiofs || strstr "$(cat /proc/filesystems)" virtiofs; }; then
         die "virtiofs is required but not available."