Stream ssl_preread: removed internal macro.

The ngx_log_debug() macro is internal and should not be used.

src/stream/ngx_stream_ssl_preread_module.c

diff --git a/src/stream/ngx_stream_ssl_preread_module.c b/src/stream/ngx_stream_ssl_preread_module.c
index f8662dd..166c093 100644
--- a/src/stream/ngx_stream_ssl_preread_module.c
+++ b/src/stream/ngx_stream_ssl_preread_module.c
@@ -137,14 +137,14 @@
     while (last - p >= 5) {
 
         if (p[0] != 0x16) {
-            ngx_log_debug(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
-                          "ssl preread: not a handshake");
+            ngx_log_debug0(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
+                           "ssl preread: not a handshake");
             return NGX_DECLINED;
         }
 
         if (p[1] != 3 || p[2] == 0) {
-            ngx_log_debug(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
-                          "ssl preread: unsupported SSL version");
+            ngx_log_debug0(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
+                           "ssl preread: unsupported SSL version");
             return NGX_DECLINED;
         }
 
@@ -230,8 +230,8 @@
 
         case sw_header:
             if (p[0] != 1) {
-                ngx_log_debug(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
-                              "ssl preread: not a client hello");
+                ngx_log_debug0(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
+                               "ssl preread: not a client hello");
                 return NGX_DECLINED;
             }