Fix a detection of 64-bit architecture
Fix a detection of 64-bit architecture

This CL fixes a detection of 64-bit architecture when /sbin/init is
symlink. On Ubuntu 15.04, /sbin/init is symlink to /lib/systemd/systemd
and therefore the |file| command doesn't show anything except the path
it refers to.

BUG=
TEST=
R=primiano@chromium.org,sbc@chromium.org,scottmg@chromium.org

Review URL: https://codereview.chromium.org/1300613002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#349373}

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