Update configure to properly detect libressl without breaking openssl compatibility

libressl is the new openbsd fork of openssl.  http://www.libressl.org  I was performing libressl compatibility testing on my gentoo linux system and discovered that AFFLIB generated a fatal error during configure: it was not able to detect a ussable openssl installation.

Openssl's libssl linked sucessfully with -lssl, but libressl's libssl requires both -lssl and -lcrypto.  Both can link against libcrypto with just -lcrypto.

AFFLIB's configure script checks for libssl before libcrypto, so the libssl check uses just -lssl and fails with libressl.  Simply changing the order of the tests resolves the issue.  By checking libcrypto first, -lcrypto is added to configure's $LIBS, so the libssl test will use both -lssl and -lcrypto.

This pull request implements that change.  I have tested with both openssl 1.0.1h and libressl 2.0.5 on my gentoo linux system.  In both cases the updated configure script detects the openssl installation properly and compiles without errors.