drrun warnings about missing other-arch libraries in non-official custom install dir are noisy

Created by: algr

$ which drrun
/tools/dynamorio/bin64/drrun
$ `which drrun` -- ls
WARNING: cannot find /tools/dynamorio/bin64/../lib32/debug/libdrpreload.so: is this an incomplete installation?
WARNING: cannot find /tools/dynamorio/bin64/../lib32/debug/libdynamorio.so: is this an incomplete installation?
WARNING: cannot find /tools/dynamorio/bin64/../lib32/release/libdrpreload.so: is this an incomplete installation?
WARNING: cannot find /tools/dynamorio/bin64/../lib32/release/libdynamorio.so: is this an incomplete installation?
WARNING: /tools/dynamorio/bin64/.. does not appear to be a valid DynamoRIO root

It's unclear why it's looking for the 32-bit libraries, or whether that is the reason why it thinks the root is invalid.