* dtable.h (dtable::build_fhandler): Make path_conv parameter non-optional.

* dtable.h (dtable::build_fhandler): Make path_conv parameter non-optional.
(dtable::init_std_file_from_handle): Eliminate name parameter.
* dtable.cc (stdio_init): Don't pass bogus name to init_std_file_from_handle.
The function will figure out the name itself.
(dtable::init_std_file_from_handle): Eliminate name parameter.  Assume that
we're always called with an appropriate fd.  Pass name as NULL if we can't
simply figure it out from context.
(cygwin_attach_handle_to_fd): Pass path_conv argument to build_fhandler.
(dtable::build_fhandler): Make path_conv argument mandatory.  Eliminate
specific call to get_device_number.  With unknown device names, set name from
handle context for parsing by path_conv.
(dtable::build_fhandler): Pass path_conv argument to build_fhandler.
* path.h (path_conv::set_isdisk): Set disk device type.
(path_conv::is_device): Don't consider FH_DISK a "device".
* syscalls.cc (_open): Pass path_conv argument by reference.
(stat_worker): Ditto.
(_rename): Use path_conv operators.  Add bounds to DeleteFile/MoveFile for
loop.