Some files were named 𝑥_test.txt and some 𝑥_tests.txt. This change
unifies around the latter.
Change-Id: Id6f29bad8b998f3c3466655097ef593f7f18f82f
Reviewed-on: https://boringssl-review.googlesource.com/8150
Reviewed-by: David Benjamin <davidben@google.com>
