Replicate the logic in the AllTests targets to dump the error queue on
failure. GTest seems to print to stdout, so we do here too.

BUG=129

Change-Id: I623b695fb9a474945834c3653728f54e5b122187
Reviewed-on: https://boringssl-review.googlesource.com/13623
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>