fix building by gcc 4.x with -O2/3/s in some Linux distributions:
   dereferencing type-punned pointer will break strict-aliasing rules
the bug has been introduced in r3065

src/http/ngx_http.h

diff --git a/src/http/ngx_http.h b/src/http/ngx_http.h
index b717c80..bb19daf 100644
--- a/src/http/ngx_http.h
+++ b/src/http/ngx_http.h
@@ -94,7 +94,7 @@
 void ngx_http_request_empty_handler(ngx_http_request_t *r);
 
 
-#define ngx_http_ephemeral(r)  (ngx_http_ephemeral_t *) (&r->uri_start)
+#define ngx_http_ephemeral(r)  (void *) (&r->uri_start)
 
 
 #define NGX_HTTP_LAST   1