Skip 909 & 126 with zipapex

Tests 909 and 126 fail on zipapex due to their 'run' scripts doing
non-standard things. Add support for run-test skipping based on a
'zipapex' selector and add these tests to the skip list.

Test: ./test/testrunner.py --no-build-dependencies --runtime-zipapex <path> -t 909 -t 910
Bug: 135507613
Change-Id: I75c103f90d73c8703649e9370c9dfc8059dd858d
diff --git a/test/knownfailures.json b/test/knownfailures.json
index 069cecb..8840de5 100644
--- a/test/knownfailures.json
+++ b/test/knownfailures.json
@@ -1278,5 +1278,11 @@
         "variant": "gcstress",
         "bug": "b/137887811",
         "description": ["Occasional timeouts."]
+    },
+    {
+        "tests": ["909-attach-agent", "126-miranda-multidex"],
+        "zipapex": true,
+        "bug": "b/135507613",
+        "description": ["These tests run dalvikvm multiple times, this can messup the zipapex runner"]
     }
 ]