Add tests to expected failures.

Test: libcore.libcore.util.NativeAllocationRegistryTest
Bug: 160885166
Change-Id: If338aba2fc6d272751e953d7a83798ea0afac4ca
diff --git a/tools/libcore_failures.txt b/tools/libcore_failures.txt
index 1280038..ac77314 100644
--- a/tools/libcore_failures.txt
+++ b/tools/libcore_failures.txt
@@ -283,5 +283,14 @@
           "libcore.javax.net.ssl.DefaultHostnameVerifierTest#testSubjectWithWildAltNamesCert",
           "libcore.javax.net.ssl.DefaultHostnameVerifierTest#testWildAltNameOnlyCert"],
   bug: 166619732
+},
+{
+  description: "Flakey tests",
+  result: EXEC_FAILED,
+  names: ["libcore.libcore.util.NativeAllocationRegistryTest#testNativeAllocationMallocNoSharedRegistry",
+          "libcore.libcore.util.NativeAllocationRegistryTest#testNativeAllocationMallocSharedRegistry",
+          "libcore.libcore.util.NativeAllocationRegistryTest#testNativeAllocationNonmallocNoSharedRegistry",
+          "libcore.libcore.util.NativeAllocationRegistryTest#testNativeAllocationNonmallocSharedRegistry"],
+  bug: 160885166
 }
 ]