Update bot config for clang/asan mac bots 10.6 -> 10.7
Update bot config for clang/asan mac bots 10.6 -> 10.7

Note the Mac Clang trybot is still 10.6.

BUG= none
TEST= none
R=bsy@google.com

Review URL: https://codereview.chromium.org/23445008

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@12066 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

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