Skip CompressCheckerboard unit test on N6.

This is at least one of the failures making the bot red.
The particular signal indicates it's probably an alignment problem.

BUG=skia:5637
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2245063002

CQ_INCLUDE_TRYBOTS=master.client.skia.android:Test-Android-GCC-Nexus6-CPU-NEON-Arm7-Debug-Trybot

TBR=robertphillips@google.com

Review-Url: https://codereview.chromium.org/2245063002
diff --git a/infra/bots/recipes/swarm_test.py b/infra/bots/recipes/swarm_test.py
index 65ec693..2be1195 100644
--- a/infra/bots/recipes/swarm_test.py
+++ b/infra/bots/recipes/swarm_test.py
@@ -286,6 +286,9 @@
   if 'Valgrind' in bot: # skia:3021
     match.append('~Threaded')
 
+  if 'Nexus6' in bot:  # skia:5637
+    match.append('~CompressCheckerboard')
+
   if 'GalaxyS3' in bot:  # skia:1699
     match.append('~WritePixels')