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/environ.h

@@ -0,0 +1,40 @@
+/* environ.h: Declarations for environ manipulation
+
+   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. */
+
+/* Initialize the environment */
+void environ_init (char **);
+
+/* The structure below is used to control conversion to/from posix-style
+ * file specs.  Currently, only PATH and HOME are converted, but PATH
+ * needs to use a "convert path list" function while HOME needs a simple
+ * "convert to posix/win32".  For the simple case, where a calculated length
+ * is required, just return MAX_PATH.  *FIXME*
+ */
+struct win_env
+  {
+    const char *name;
+    size_t namelen;
+    char *posix;
+    char *native;
+    int (*toposix) (const char *, char *);
+    int (*towin32) (const char *, char *);
+    int (*posix_len) (const char *);
+    int (*win32_len) (const char *);
+    void add_cache (const char *in_posix, const char *in_native = NULL);
+    const char * get_native () {return native ? native + namelen : NULL;}
+  };
+
+win_env * __stdcall getwinenv (const char *name, const char *posix = NULL);
+
+void __stdcall update_envptrs ();
+char * __stdcall winenv (const char * const *, int);
+extern char **__cygwin_environ, ***main_environ;
+extern "C" char __stdcall **cur_environ ();
+int __stdcall envsize (const char * const *, int debug_print = 0);