PPC/AIX : skip regex test case

Regex test cases fails on AIX debug due to stack-overflow.

R=miladfar@ca.ibm.com, joransiu@ca.ibm.com, jyan@ca.ibm.com

Bug: 
Change-Id: I217ad3d61fa8d7572cc0c7e25efa63065552f99a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1625836
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61976}

test/mjsunit/mjsunit.status

@@ -895,6 +895,12 @@
   'regress/regress-353551': [SKIP],
 }],  # 'arch == ppc64'
 
+##############################################################################
+['system == aix', {
+  # stack overflow
+  'regress/regress-crbug-178790': [PASS, ['mode == debug', SKIP]],
+}],  # 'system == aix'
+
 ##############################################################################
 ['arch == s390x', {
   # stack overflow