Revert "feature: updated the NGINX patches for async SSL session fetching to support OpenSSL 1.1.1."

This reverts commit 9e834398de.

Support for OpenSSL 1.1.1 will come with the 1.17.1 series of NGINX
patches. Since no other 1.15.8.* releases are planned, we are reverting
the state of the 1.15.8 patches to that of the 1.15.8.1 release.

patches/nginx-1.15.8-ssl_pending_session.patch

@@ -1,6 +1,6 @@
 --- nginx-1.15.8/src/event/ngx_event_openssl.c	2016-07-17 19:20:30.411137606 -0700
 +++ nginx-1.15.8-patched/src/event/ngx_event_openssl.c	2016-07-19 16:53:35.539768477 -0700
-@@ -1581,7 +1581,15 @@ ngx_ssl_try_early_data(ngx_connection_t *c)
+@@ -1307,7 +1307,12 @@ ngx_ssl_handshake(ngx_connection_t *c)
      }
  
  #if OPENSSL_VERSION_NUMBER >= 0x10002000L
@@ -8,27 +8,9 @@
 +    if (sslerr == SSL_ERROR_WANT_X509_LOOKUP
 +#   ifdef SSL_ERROR_PENDING_SESSION
 +        || sslerr == SSL_ERROR_PENDING_SESSION
-+
-+#   elif defined(SSL_ERROR_WANT_CLIENT_HELLO_CB)
-+        || sslerr == SSL_ERROR_WANT_CLIENT_HELLO_CB
 +#   endif
 +       )
 +    {
          c->read->handler = ngx_ssl_handshake_handler;
          c->write->handler = ngx_ssl_handshake_handler;
  
-diff --git a/src/event/ngx_event_openssl.h b/src/event/ngx_event_openssl.h
---- a/src/event/ngx_event_openssl.h
-+++ b/src/event/ngx_event_openssl.h
-@@ -64,6 +64,11 @@
- #endif
- 
- 
-+#ifdef SSL_ERROR_WANT_CLIENT_HELLO_CB
-+#define HAVE_SSL_CLIENT_HELLO_CB_SUPPORT  1
-+#endif
-+
-+
- struct ngx_ssl_s {
-     SSL_CTX                    *ctx;
-     ngx_log_t                  *log;