wrapper: print android-llvm@ when using the Android wrapper.

Otherwise, the wrapper might say:

```
Internal error. Please report to chromeos-toolchain@google.com.
```

to Android developers in some cases.

BUG=b:159291805
TEST=`go test`

Change-Id: I9a96068f02a2c6ce5e251c8754e267dfb1a30db1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2252553
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>
3 files changed