Include a more modest openssl header in crypto_openssl_mgt.h

The "engines.h" header has lots of stuff; the "opensslv.h" header
has the version number, which is all we actually need here.

We need to do this because we're about to change this header to
conditionally define OPENSSL_SUPPRESS_DEPRECATED, and it would be
too late to do so if we'd already included "engines.h".

src/lib/crypt_ops/crypto_openssl_mgt.h

@@ -16,8 +16,7 @@
 #include "orconfig.h"
 
 #ifdef ENABLE_OPENSSL
-#include <openssl/engine.h>
-
+#include <openssl/opensslv.h>
 /*
   Macro to create an arbitrary OpenSSL version number as used by
   OPENSSL_VERSION_NUMBER or SSLeay(), since the actual numbers are a bit hard