fix compiler warnings for SSL-disabled builds

lib/sslgen.c

@@ -609,6 +609,9 @@ bool Curl_ssl_data_pending(struct connectdata *conn,
   if(conn->ssl[connindex].handle)
     /* SSL is in use */
     return SSL_pending(conn->ssl[connindex].handle);
+#else
+  (void)conn;
+  (void)connindex;
 #endif
   return FALSE; /* nothing pending */
 

lib/sslgen.h

@@ -77,7 +77,6 @@ bool Curl_ssl_data_pending(struct connectdata *conn,
 #if !defined(USE_SSL) && !defined(SSLGEN_C)
 /* set up blank macros for none-SSL builds */
 #define Curl_ssl_close_all(x)
-#define Curl_ssl_data_pending(x,y) 0
 #endif
 
 #define SSL_SHUTDOWN_TIMEOUT 10000 /* ms */