[NaCl SDK] Fix bionic SDK build
[NaCl SDK] Fix bionic SDK build

This was broken by my recent change to enable arm-glibc.

CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:linux_nacl_sdk

Review URL: https://codereview.chromium.org/1246133002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#339773}

Chilledheart/chromium,axinging/chromium-crosswalk,Chilledheart/chromium,Just-D/chromium-1,Chilledheart/chromium,Just-D/chromium-1,Just-D/chromium-1,Chilledheart/chromium,axinging/chromium-crosswalk,Just-D/chromium-1,axinging/chromium-crosswalk,Chilledheart/chromium,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,Just-D/chromium-1,axinging/chromium-crosswalk,Just-D/chromium-1,axinging/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Just-D/chromium-1,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,Just-D/chromium-1,axinging/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,Chilledheart/chromium,Chilledheart/chromium,Just-D/chromium-1