Windows doesn't like struct literals:
..\decrepit\dsa\dsa_decrepit.c(85) : warning C4204: nonstandard extension used : non-constant aggregate initializer

Change-Id: I12541f2883ecbb10c85cddfae8d2adbbb1365ae3
Reviewed-on: https://boringssl-review.googlesource.com/7364
Reviewed-by: Adam Langley <agl@google.com>