Disable a slow test under Valgrind.
Disable a slow test under Valgrind.

TEST=none
BUG=http://code.google.com/p/nativeclient/issues/detail?id=2843
Review URL: https://chromiumcodereview.appspot.com/10542136

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@8914 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client,sbc100/native_client,nacl-webkit/native_client,nacl-webkit/native_client