Break out more header info into separate files. Use appropriate header files

throughout.
* shared.h: Remove.
* cygwin_version.h: New file.
* delqueue.h: New file.
* environ.h: New file.
* host_dependent.h: New file.
* perprocess.h: New file.
* registry.h: New file.
* security.h: New file.

winsup/cygwin/registry.cc

@@ -9,8 +9,10 @@ Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
 details. */
 
 #include "winsup.h"
-#include "tty.h"
 #include "shared_info.h"
+#include "registry.h"
+#include "security.h"
+#include <cygwin/version.h>
 
 char cygnus_class[] = "cygnus";