mklive.sh: Use overlayfs for live image writable overlay.

mklive.sh.in

@@ -319,8 +319,9 @@ while getopts "a:b:r:c:C:T:Kk:l:i:I:s:S:o:p:h" opt; do
     esac
 done
 shift $((OPTIND - 1))
-
 XBPS_REPOSITORY="$XBPS_REPOSITORY --repository=http://alpha.de.repo.voidlinux.org/current --repository=http://alpha.de.repo.voidlinux.org/current/musl"
+# Configure dracut to use overlayfs for the writable overlay.
+BOOT_CMDLINE="$BOOT_CMDLINE rd.live.overlay.overlayfs=1 "
 
 ARCH=$(xbps-uhelper arch)