Bug 1545217 - Skip gtest TestThreads.cpp on android again; r=jmaher

I enabled this test yesterday, but it turns out it still crashes intermittently:
https://treeherder.mozilla.org/logviewer.html#?job_id=245063009&repo=autoland
https://taskcluster-artifacts.net/DJEiHJaJRaCYMWk2UMoR8A/0/public/test_info//logcat-emulator-5554.log
05-07 08:47:38.460  2530  2545 I gtest   : TEST-START | Threads.Main
--------- beginning of crash
05-07 08:47:38.570  2530  2545 F libc    : stack corruption detected
05-07 08:47:38.570  2530  2545 W google-breakpad: ExceptionHandler::GenerateDump cloned child

Differential Revision: https://phabricator.services.mozilla.com/D30198

--HG--
extra : moz-landing-system : lando

xpcom/tests/gtest/moz.build

@@ -56,7 +56,6 @@ UNIFIED_SOURCES += [
     'TestThreadMetrics.cpp',
     'TestThreadPool.cpp',
     'TestThreadPoolListener.cpp',
-    'TestThreads.cpp',
     'TestThrottledEventQueue.cpp',
     'TestTimeStamp.cpp',
     'TestTokenizer.cpp',
@@ -66,6 +65,7 @@ UNIFIED_SOURCES += [
 if CONFIG['OS_TARGET'] != 'Android':
     UNIFIED_SOURCES += [
         'TestPipes.cpp',
+        'TestThreads.cpp',
     ]
 
 # skip the test on windows10-aarch64 due to perma-fail, bug 1422219