PPC/s390x: skip atomics(64)-stress on sim

simulator takes too long to run.

Change-Id: I77f6e932129bfed7d1cdb7e9ccf78a4608554ff5
Reviewed-on: https://chromium-review.googlesource.com/c/1320389Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#57296}

test/mjsunit/mjsunit.status

@@ -774,8 +774,8 @@
   'regress/regress-91008': [PASS, SLOW],
   'harmony/regexp-property-lu-ui': [PASS, SLOW],
   'whitespaces': [PASS, SLOW],
-  'wasm/atomics-stress': [PASS, SLOW],
-  'wasm/atomics64-stress': [PASS, SLOW],
+  'wasm/atomics-stress': [SKIP],
+  'wasm/atomics64-stress': [SKIP],
 }],  # 'simulator_run and (arch == ppc or arch == ppc64 or arch == s390 or arch == s390x)'
 
 ##############################################################################