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/shortcut.c

@@ -39,7 +39,7 @@ has_exec_chars (const char *buf, int len)
 }
 
 char shortcut_header[SHORTCUT_HDR_SIZE];
-BOOL shortcut_initalized = FALSE;
+BOOL shortcut_initalized;
 
 void
 create_shortcut_header (void)