nginx-0.2.0-RELEASE import

    *) The pid-file names used during online upgrade was changed and now is
       not required a manual rename operation. The old master process adds
       the ".oldbin" suffix to its pid-file and executes a new binary file.
       The new master process creates usual pid-file without the ".newbin"
       suffix. If the master process exits, then old master process renames
       back its pid-file with the ".oldbin" suffix to the pid-file without
       suffix.

    *) Change: the "worker_connections" directive, new name of the
       "connections" directive; now the directive specifies maximum number
       of connections, but not maximum socket descriptor number.

    *) Feature: SSL supports the session cache inside one worker process.

    *) Feature: the "satisfy_any" directive.

    *) Change: the ngx_http_access_module and ngx_http_auth_basic_module do
       not run for subrequests.

    *) Feature: the "worker_rlimit_nofile" and "worker_rlimit_sigpending"
       directives.

    *) Bugfix: if all backend using in load-balancing failed after one
       error, then nginx did not try do connect to them during 60 seconds.

    *) Bugfix: in IMAP/POP3 command argument parsing.
       Thanks to Rob Mueller.

    *) Bugfix: errors while using SSL in IMAP/POP3 proxy.

    *) Bugfix: errors while using SSI and gzipping.

    *) Bugfix: the "Expires" and "Cache-Control" header lines were omitted
       from the 304 responses.
       Thanks to Alexandr Kukushkin.
diff --git a/src/os/unix/ngx_process.h b/src/os/unix/ngx_process.h
index 3684b15..06ff21c 100644
--- a/src/os/unix/ngx_process.h
+++ b/src/os/unix/ngx_process.h
@@ -13,6 +13,8 @@
 
 typedef pid_t       ngx_pid_t;
 
+#define NGX_INVALID_PID  -1
+
 typedef void (*ngx_spawn_proc_pt) (ngx_cycle_t *cycle, void *data);
 
 typedef struct {