fuzzying: enable raw public keys
Description of problem:
Currently we have fuzzers for X509 keys/certificates (gnutls_client_fuzzer.c and gnutls_server_fuzzer.c) but not for raw public keys. If we'd like both code bases to be in par in terms of quality we should enable fuzzying for raw public keys as well (see gnutls_client_fuzzer, gnutls_server_fuzzer and README-adding-traces for more info).