Disable zlib wasm embenchen for now, fails gc stress.

BUG=
TBR=titzer@chromium.org
LOG=N
NOTRY=true

Review URL: https://codereview.chromium.org/1761273002

Cr-Commit-Position: refs/heads/master@{#34477}

test/mjsunit/mjsunit.status

@@ -318,6 +318,7 @@
   'wasm/embenchen/copy': [FAIL],  # wrong answer
   'wasm/embenchen/box2d': [SKIP],   # hang
   'wasm/embenchen/lua_binarytrees': [SKIP],  # fails decode
+  'wasm/embenchen/zlib': [SKIP],  # fails gc-stress
 
   # case-insensitive unicode regexp relies on case mapping provided by ICU.
   'harmony/unicode-regexp-ignore-case': [PASS, ['no_i18n == True', FAIL]],