* include/cygwin/version.h: Bump API minor number to 151.

* include/cygwin/version.h: Bump API minor number to 151.
* dir.cc (__opendir_with_d_ino): New function.
(opendir): Set flag if we should be calculating inodes.
(readdir_worker): Calculate d_ino by calling stat if the user has asked for it.
(seekdir64): Maintain all persistent flag settings.
* fhandler.h (dirent_states): Add dirent_set_d_ino.
* fhandler_disk_file.cc (fhandler_disk_file::opendir): Reflect changes to
dirent structure.
* fhandler_virtual.cc (fhandler_virtual::opendir): Ditto.
* include/sys/dirent.h (struct dirent): Coalesce two similar structures.
Remove all threads of the apparently highly confusing references to inodes.
Add support for calculating a real inode if __USE_EXPENSIVE_CYGWIN_D_INO is
defined.