Fixed missing $ in buildbot_toolchain.sh.
Fixed missing $ in buildbot_toolchain.sh.

R=bradnelson@google.com
BUG=None
TEST=trybots

Review URL: https://codereview.chromium.org/742783004

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@14120 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client