Win32: MinGW GCC compatibility. Several warnings silenced, notably (ngx_socket_t) -1 is now checked on socket operations instead of -1, as ngx_socket_t is unsigned on win32 and gcc complains on comparison. With this patch, it's now possible to compile nginx using mingw gcc, with options we normally compile on win32.

--- a/src/event/modules/ngx_iocp_module.c
+++ b/src/event/modules/ngx_iocp_module.c
@@ -170,7 +170,7 @@ ngx_iocp_timer(void *data)
 #endif
     }
 
-#ifdef __WATCOMC__
+#if defined(__WATCOMC__) || defined(__GNUC__)
     return 0;
 #endif
 }