Fixed debug logging in ngx_http_parse_complex_uri().

The *u previously logged isn't yet initialized at this point, and
Valgrind complains.

src/http/ngx_http_parse.c

diff --git a/src/http/ngx_http_parse.c b/src/http/ngx_http_parse.c
index 3c168aa..87a22e0 100644
--- a/src/http/ngx_http_parse.c
+++ b/src/http/ngx_http_parse.c
@@ -1256,8 +1256,8 @@
          * the line feed
          */
 
-        ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
-                       "s:%d in:'%Xd:%c', out:'%c'", state, ch, ch, *u);
+        ngx_log_debug3(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "s:%d in:'%Xd:%c'", state, ch, ch);
 
         switch (state) {