ag_any: respect target root also when the file does not exist in the original root

[boo#903747](https://bugzilla.opensuse.org/show_bug.cgi?id=903747).

Targeted for SLE12 because it is a trivial bugfix.
The reported bug would only be fixed if the fix is applied to the inst-sys (as a DUD or as a DVD respin).
Do you mean
```bash
export LD_LIBRARY_PATH=$ROOT/liby2util-r/$LIB:$ROOT/libycp/$LIB:$ROOT/liby2/$LIB:$ROOT/libscr/$LIB:$ROOT/wfm/$LIB:$ROOT/scr/$LIB
```

But then the line, which is already quite long, would be even longer and IMHO less readable.