Make sure that waitpid returns something usefull on OS/2. Avoids the "Unknown

SANE status code 128" errors.
Henning Meier-Geinitz <henning@meier-geinitz.de>

sanei/sanei_thread.c

@@ -81,6 +81,8 @@ sanei_thread_kill( int pid, int sig)
 int
 sanei_thread_waitpid( int pid, int *stat_loc, int options)
 {
+  if (stat_loc)
+    *stat_loc = 0;
   return pid; /* DosWaitThread( (TID*) &pid, DCWW_WAIT);*/
 }