Ensure all EVP calls have their returns checked where appropriate

There are lots of calls to EVP functions from within libssl There were
various places where we should probably check the return value but don't.
This adds these checks.

Reviewed-by: Richard Levitte <levitte@openssl.org>

ssl/ssl.h

@@ -2681,6 +2681,7 @@ void ERR_load_SSL_strings(void);
 # define SSL_F_SSL3_DO_CHANGE_CIPHER_SPEC                 292
 # define SSL_F_SSL3_ENC                                   134
 # define SSL_F_SSL3_GENERATE_KEY_BLOCK                    238
+# define SSL_F_SSL3_GENERATE_MASTER_SECRET                388
 # define SSL_F_SSL3_GET_CERTIFICATE_REQUEST               135
 # define SSL_F_SSL3_GET_CERT_STATUS                       289
 # define SSL_F_SSL3_GET_CERT_VERIFY                       136