live/x86.tmpl: Copy livecd-iso-to-disk script, if installed

A post-installation script in fedora-live-base.ks actually modifies
Lorax (not idempotently) with the change in this commit while it is
running. This modification belongs directly in Lorax instead.

Note a subtle distinction in behavior that has been preserved here.
Lorax will copy the livecd-iso-to-disk script from the installroot
(if present). Running livecd-creator will copy it from the existing
root filesystem instead.

share/templates.d/99-generic/live/x86.tmpl

@@ -112,6 +112,12 @@ hardlink ${KERNELDIR}/initrd.img ${BOOTDIR}
     <% filegraft += " {0}={1}/{0}".format(basename(f), outroot) %>
 %endfor
 
+# Add the livecd-iso-to-disk script if installed
+<% f = "usr/bin/livecd-iso-to-disk" %>
+%if exists(f):
+    install ${f} ${LIVEDIR}/${f|basename}
+%endif
+
 ## make boot.iso
 runcmd xorrisofs ${isoargs} -o ${outroot}/images/boot.iso \
        -isohybrid-mbr /usr/share/syslinux/isohdpfx.bin \