Blacklist 137-cfi on target 32.

Bug: 147910661
Test: test.py
Change-Id: I50d3e73551744af3aa5a35a63660f64326150e4d
diff --git a/test/knownfailures.json b/test/knownfailures.json
index 3574698..0a4d2bb 100644
--- a/test/knownfailures.json
+++ b/test/knownfailures.json
@@ -96,6 +96,12 @@
                         "slowness of gcstress makes this bad."]
     },
     {
+        "tests": "137-cfi",
+        "variant": "target & 32",
+        "description": ["Flakes in unwinding on armv7."],
+        "bug": "b/147910661"
+    },
+    {
         "tests": "152-dead-large-object",
         "variant": "gcstress",
         "description": ["152-dead-large-object requires a heap larger than what gcstress uses."],