TBR: tools/lib/testutil: don't fail on empty xUnit file.
TBR: tools/lib/testutil: don't fail on empty xUnit file.

Change-Id: I363c17d8e40728cae86b9a057dbba1ebf8f2b37c

vanadium/go.devtools,vanadium/go.devtools,vanadium/go.devtools