Add test 071-dexfile to skips for gcstress

Like some other tests it can send error messages due to the
backtracing being slower.

Test: Treehugger
Bug: 111543628
Change-Id: I8bece29c8c875ff578a17ab72e48baa8b232a160
diff --git a/test/knownfailures.json b/test/knownfailures.json
index 44a5c12..d4e4ad4 100644
--- a/test/knownfailures.json
+++ b/test/knownfailures.json
@@ -1016,7 +1016,7 @@
         "description" : ["Gcstress requires the ability to open at least one file which means this test fails when it runs out."]
     },
     {
-        "tests": ["530-checker-lse2", "141-class-unload"],
+        "tests": ["530-checker-lse2", "141-class-unload", "071-dexfile"],
         "variant": "gcstress",
         "bug": "b/111543628",
         "description" : ["Test seems to timeout when run with gcstress due to slower unwinding by libbacktrace"]