* cygwin.sc: New file -- linker script for building cygwin DLL.

* cygwin.sc: New file -- linker script for building cygwin DLL.
* Makefile.in: Use linker script to control location of cygheap.
* cygheap.cc (buckets): Make static.
(init_cheap): Remove special iswinnt handling.  Allocate cygheap at a fixed
location.  Display more info when allocation fails.
(cygheap_fixup_in_child): Try harder to move cygheap to correct location.
Display more info when allocation fails.
* fhandler.h (fhandler_socket): Add macros for tracking socket shutdown state.
* net.cc (cygwin_shutdown): Set appropriate shutdown value for future use.
* select.cc (select_stuff::cleanup): New method.
(cygwin_select): Call cleanup explicitly to avoid a race.
(select_stuff:~select_stuff): Call cleanup chain via cleanup method.
(fhandler_socket::select_read): Set *_ready when shutdown has been called on
the socket.
(fhandler_socket::select_write): Ditto.
(fhandler_socket::select_except): Ditto.
* winsup.h: Move NO_COPY to "COMMON" section.
* autoload.cc (wsock_started): Avoid initializing NO_COPY value.
* sigproc.cc: Remove initialization from NO_COPY variables.
(sigproc_init): Initialize sig_loop_wait here, rather than via initialization.
(subproc_init): Initialize proc_loop_wait here, rather than via initialization.