Turn on exceptions in test tools.

This allows us to test things that, e.g., throw std::bad_alloc.

Change-Id: I6409159b89f1d93d403b1a1f40539cf2531a8b68
Reviewed-on: https://skia-review.googlesource.com/34982
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
4 files changed