Apr-Util compatibility with OpenSSL 1.1.0

[Bert Huijben]

        Hi,

I just tried using OpenSSL 1.1.0-pre4 with APR-UTIL and found that the code
is incompatible. The file apr_crypto_openssl.c fails to compile as some
structs have been made opaque.

I can probably provide a patch later, but perhaps others want to know about
the problem before that.

        Bert