* 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/path.h

@@ -36,7 +36,6 @@ enum path_types
   PATH_BINARY = MOUNT_BINARY,
   PATH_EXEC = MOUNT_EXEC,
   PATH_CYGWIN_EXEC = MOUNT_CYGWIN_EXEC,
-  PATH_NEEDDIR = 0x20000000,
   PATH_SOCKET =  0x40000000,
   PATH_HASACLS = 0x80000000
 };