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/perprocess.h

@@ -0,0 +1,20 @@
+/* per_process.h: main Cygwin header file.
+
+   Copyright 2000 Red Hat, Inc.
+
+This file is part of Cygwin.
+
+This software is a copyrighted work licensed under the terms of the
+Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
+details. */
+
+#include <sys/cygwin.h>
+
+/* Pointer into application's static data */
+extern "C" per_process __cygwin_user_data;
+#define user_data (&__cygwin_user_data)
+
+/* We use the following to test that sizeof hasn't changed.  When adding
+   or deleting members, insert fillers or use the reserved entries.
+   Do not change this value. */
+#define SIZEOF_PER_PROCESS (42 * 4)