Since we no longer have a 32-bit Linux GN binary, we shouldn't
try to point to one in the gn.py wrapper; this was hiding a
bug on one of the NaCl bots.

R=brettw@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1152163008

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@295520 0039d316-1c4b-4281-b951-d872f2087c98