The wolfSSL's OpenSSL compatibility layer is not used by the plugin at
all and preventing its inclusion avoids conflicts with ASN1_ constants.
The inclusion of wolfssl/ssl.h is moved to the only file that requires
it as older wolfSSL versions defined a conflicting ASN1_GENERALIZEDTIME.
Other changes address issues with the FIPS use case.
Closesstrongswan/strongswan#1332
