set the default compiler to llvm.

Since we finished the migration to llvm. So we need
to set the default compiler string to llvm.

BUG=None
TEST=The default compiler is set to llvm.

Change-Id: I2d58c2850af5cc4d5f3a13e7bd2a68cd41d3ffb0
Reviewed-on: https://chromium-review.googlesource.com/457263
Commit-Ready: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
1 file changed