Switch EVP_PKEY_dup calls to EVP_PKEY_up_ref.

Keep internal callers up-to-date with deprecations.

Change-Id: I7ee171afc669592d170f83bd4064857d59332878
Reviewed-on: https://boringssl-review.googlesource.com/4640
Reviewed-by: Adam Langley <agl@google.com>
6 files changed