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/malloc_wrapper.cc

@@ -17,6 +17,7 @@ details. */
 #include "cygheap.h"
 #include "heap.h"
 #include "sync.h"
+#include "perprocess.h"
 
 /* we provide these stubs to call into a user's
    provided malloc if there is one - otherwise