Update libcore expectations for gcstress+debug+host

Mark a couple of tests as failing:

* libcore.java.lang.ThreadTest#nativeThreadNames
* jsr166.ThreadLocalTest#testGenericITL

These are failing on the bots but do not repro locally.

Bug: 189826569
Test: art/tools/run-libcore-tests.sh --mode host -j 36 --gcstress \
        --debug libcore.java.lang.ThreadTest#nativeThreadNames
Change-Id: Ia1a6405c001f9bafecdcbcc2af6ab26339dcb541
diff --git a/tools/libcore_gcstress_debug_failures.txt b/tools/libcore_gcstress_debug_failures.txt
index a5422af..64d75a3 100644
--- a/tools/libcore_gcstress_debug_failures.txt
+++ b/tools/libcore_gcstress_debug_failures.txt
@@ -46,5 +46,14 @@
           "org.apache.harmony.tests.java.lang.ProcessManagerTest#testSleep",
           "org.apache.harmony.tests.java.math.BigIntegerConstructorsTest#testConstructorPrime"
   ]
+},
+{
+  description: "Stack unwinding failures on LUCI hosts with gcstress and debug.",
+  bug: 189826569,
+  result: ERROR,
+  modes: [host],
+  names: ["libcore.java.lang.ThreadTest#nativeThreadNames",
+          "jsr166.ThreadLocalTest#testGenericITL"
+  ]
 }
 ]