Change Lunix builds to force 32-bit.  Added a TODO to enable 64-bit when the runtime is supported.
Change Lunix builds to force 32-bit.  Added a TODO to enable 64-bit when the
runtime is supported.

Review URL: http://codereview.chromium.org/1606011

git-svn-id: e22621a84199d42b34715cdc089545aeedbbf23f@122 050acbb0-2703-11df-ab0a-9f3f633ae91d

sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk