[tests] Skip RuntimeCallStatsTest due to flaky timers

R=machenbach@chromium.org
BUG=v8:5677
NOTRY=true

Review-Url: https://codereview.chromium.org/2528363002
Cr-Commit-Position: refs/heads/master@{#41305}

test/unittests/unittests.status

@@ -3,6 +3,11 @@
 # found in the LICENSE file.
 
 [
+[ALWAYS, {
+    # BUG(5677): Real timers are flaky
+    'RuntimeCallStatsTest.*': [SKIP],
+}], # ALWAYS
+
 ['arch == x87', {
   'Ieee754.Expm1': [SKIP],
   'Ieee754.Cos': [SKIP],