mklive.sh: remove installing local installer

There used to be a package that provided the installer, it was removed
in 2013 and replaced by the installer.sh script in the void-mklive repository,
so this code path doesn't make sense on modern void systems.

https://github.com/void-linux/void-packages/commit/59a5c8461e9152571bc25c6e4e0d4b13a8529f06

mklive.sh.in

@@ -133,11 +133,7 @@ install_packages() {
     fi
     chroot "$ROOTFS" env -i xbps-reconfigure -a
 
-    if [ -x installer.sh ]; then
-        install -Dm755 installer.sh "$ROOTFS"/usr/sbin/void-installer
-    else
-        install -Dm755 /usr/sbin/void-installer "$ROOTFS"/usr/sbin/void-installer
-    fi
+    install -Dm755 installer.sh "$ROOTFS"/usr/sbin/void-installer
     # Cleanup and remove useless stuff.
     rm -rf "$ROOTFS"/var/cache/* "$ROOTFS"/run/* "$ROOTFS"/var/run/*
 }