Rename the test_stack recipe file name to be consistent with the rest of the

tests.

[skip ci]

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2964)

diff --git a/test/recipes/02-test-stack.t b/test/recipes/02-test_stack.t
similarity index 100%
rename from test/recipes/02-test-stack.t
rename to test/recipes/02-test_stack.t