Get signature length with EVP_DigestSign() for bssl am: 14fbc4210d

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/openssl/+/2165869

Change-Id: I55366466b327a624af4a72e472313794585348ce
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>