Mark known failure for varhandle concurrency test

Bug: 224733324
Test: art/test/testrunner/testrunner.py --target -t 719-varhandle-concurrency
Change-Id: If0e392e2ff3834b014764f92867b1e61d9b52dc9
diff --git a/test/knownfailures.json b/test/knownfailures.json
index 9750ba7..c5bad79 100644
--- a/test/knownfailures.json
+++ b/test/knownfailures.json
@@ -1498,5 +1498,11 @@
                   "640-checker-integer-valueof"],
         "variant": "optimizing & no-image",
         "description": ["Expected failures when compiling without a boot image"]
+    },
+    {
+        "tests": ["719-varhandle-concurrency"],
+        "variant": "target & ndebug & 64",
+        "bug": "b/224733324",
+        "description": ["segfault in VarHandle::GetMethodTypeMatchForAccessMode"]
     }
 ]