Remove initialization of static or global values to zero, throughout. This

just needlessly grows the size of the DLL.
* tty.cc (tty::alive): Make inuse handle non-inheriting on open, just for
thread safety.

winsup/cygwin/external.cc

@@ -35,7 +35,7 @@ fillout_pinfo (pid_t pid, int winpid)
   if (!pids.npids || !nextpid)
     pids.init (winpid);
 
-  static unsigned int i = 0;
+  static unsigned int i;
   if (!pid)
     i = 0;