tools: refine inclusion of debug failures to avoid fugu

Fugu expectations overlap with debug expectations which vogar then
rejects because of duplicates.

Test: art/tools/run-libcore-tests.sh --mode=device --debug --
  libcore.java.math.BigIntegerTest
Bug: 181968447
Change-Id: Ic73932108b9949e2b0b06eae2e251f94b3cae63d
1 file changed