Fix pnacl driver tests to look for x64 host dir when x86-32 isn't built
Fix pnacl driver tests to look for x64 host dir when x86-32 isn't built

BUG=none

The failing bots have timeouts or other artifacts :-/

Review URL: https://codereview.chromium.org/11743040

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@10538 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

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