Fix s_server -WWW with -async

The s_server option -WWW was not async aware, and therefore was not
handling SSL_ERROR_WANT_ASYNC conditions. This commit fixes that.

Reviewed-by: Rich Salz <rsalz@openssl.org>

apps/s_server.c

diff --git a/apps/s_server.c b/apps/s_server.c
index da09352..548eacb 100644
--- a/apps/s_server.c
+++ b/apps/s_server.c
@@ -2662,7 +2662,7 @@
     for (;;) {
         i = BIO_gets(io, buf, bufsize - 1);
         if (i < 0) {            /* error */
-            if (!BIO_should_retry(io)) {
+            if (!BIO_should_retry(io) && !SSL_waiting_for_async(con)) {
                 if (!s_quiet)
                     ERR_print_errors(bio_err);
                 goto err;
@@ -2929,7 +2929,7 @@
 #endif
                     k = BIO_write(io, &(buf[j]), i - j);
                     if (k <= 0) {
-                        if (!BIO_should_retry(io))
+                        if (!BIO_should_retry(io)  && !SSL_waiting_for_async(con))
                             goto write_error;
                         else {
                             BIO_printf(bio_s_out, "rwrite W BLOCK\n");