* dcrt0.cc (do_global_dtors): Run DLL dtors.

(__main): Don't rely on atexit to run dtors.
(do_exit): Specifically call do_global_dtors here.
(cygwin_exit): Ditto.
* dll_init.cc (dll_global_dtors): Make global.  Only run dtors once.
(dll_list::init): Just set flag that dtors should be run.  Don't rely on
atexit.
* dll_init.h (dll_global_dtors): Declare.
* exceptions.cc (sigrelse): Define.
* path.h (is_fs_device): New method.
(is_lnk_special): Ditto.
* fhandler_disk_file.cc (fhandler_disk_file::link): Use "is_lnk_special" rather
than "is_lnk_symlink".
* syscalls.cc (rename): Ditto.
* hookapi.cc (ld_preload): Use colon as a separator rather than space.

winsup/cygwin/dll_init.h

@@ -89,3 +89,4 @@ public:
 };
 
 extern dll_list dlls;
+void dll_global_dtors ();