We can use hashLengthInternal() to check if the buffer is big enough.
This matches what the QCH::hash() method does, it also has an assert
that `result.size() == ba.size()`, so we can assume this works with
OpenSSL's EVP_MD_get_size() in EVP::finalizeUnchecked().
Amends c70c81b371993ca865d523bb5f37eac4eb8a972b.
Pick-to: 6.8
Change-Id: I64935f3d590ab243b361a0b764f011c388820e32
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
(cherry picked from commit b83e825fab16f83f86149ead78efb6ec3d2fa16d)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
cc369ad07f