Add missing include file

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%401787

src/thread/pth/SDL_systhread.c

@@ -27,12 +27,13 @@
  *	Patrice Mandin
  */
 
-#include "SDL_thread.h"
-#include "../SDL_systhread.h"
-
 #include <pth.h>
 #include <signal.h>
 
+#include "SDL_thread.h"
+#include "../SDL_thread_c.h"
+#include "../SDL_systhread.h"
+
 /* List of signals to mask in the subthreads */
 static int sig_list[] = {
 	SIGHUP, SIGINT, SIGQUIT, SIGPIPE, SIGALRM, SIGTERM, SIGCHLD, SIGWINCH,