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
diff --git a/tools/run-libcore-tests.sh b/tools/run-libcore-tests.sh
index 0be5b56..1f39e7d 100755
--- a/tools/run-libcore-tests.sh
+++ b/tools/run-libcore-tests.sh
@@ -313,7 +313,8 @@
     # of -XX:AlwayLogExplicitGcs:false.
     vogar_args="$vogar_args --vm-arg -XX:LongPauseLogThreshold=15" # 15 ms (default: 5ms)
   else
-    if $debug; then
+    # Include debug expectations if not on fugu.
+    if $debug && $getrandom; then
       expectations="$expectations --expectations art/tools/libcore_debug_failures.txt"
     fi