* net.cc (set_socket_inheritance): Rename from duplicate_socket. Use NT

specific call when appropriate.
(__set_winsock_errno): Rename from set_winsock_errno.  Accept function and line
as arguments.
* path.cc (path_conv::check): Continue the neverending battle to make cygwin
properly understand that path specs ending in a slash require that the path
refer to a directory.  Windows does not do this by default.
(symlink_info::check): Remove ENOTDIR test.  Move it to path_conv::check.
* path.h: Remove obsolete constant.
* winsup.h (set_winsock_errno): New macro.

winsup/cygwin/winsup.h

@@ -201,7 +201,8 @@ long __stdcall to_time_t (FILETIME * ptr);
 void __stdcall set_console_title (char *);
 void set_console_handler ();
 
-void set_winsock_errno ();
+#define set_winsock_errno() __set_winsock_errno (__FUNCTION__, __LINE__)
+void __set_winsock_errno (const char *fn, int ln);
 
 /* Printf type functions */
 extern "C" void __api_fatal (const char *, ...) __attribute__ ((noreturn));