* dtable.cc (dtable::build_fhandler_from_name): Just pass posix path along to

* dtable.cc (dtable::build_fhandler_from_name): Just pass posix path along to
set_name via return_and_clear_normalized_path.
(dtable::build_fhandler): New method with const char * argument.
(dtable::reset_unix_path_name): Eliminate.
(dtable::dup_worker): Use correct build_fhandler method.
* mmap.cc (mmap_record::alloc_fh): Ditto.
* dtable.h (dtable::build_fhandler): New method.
(dtable::reset_unix_path_name): Eliminate.
* fhandler.cc (fhandler_base::set_name): Assume that unix_name has already been
cmalloced.
(fhandler_base::reset_unix_path_name): Eliminate.
(fhandler_base::~fhandler_base): Coercion for cfree.
* fhandler.h (fhandler_base::unix_path_name): Make const char *.
(fhandler_base::win32_path_name): Ditto.
(fhandler_base::reset_unix_path_name): Eliminate.
* fhandler_disk_file.cc (fhandler_cygdrive::set_drives): Accommodate const char
*ness of win32_path_name.
* fhandler_socket.cc (fhandler_socket::fstat): Accommodate new set_name
requirements.
* path.cc (path_conv::return_and_clear_normalized_path): New method.
(path_conv::clear_normalized_path): Eliminate.
(path_conv::~path_conv): Ditto.
(path_conv::check): Accommodate new build_fhandler method.
* path.h (path_conv::~path_conv): Eliminate.
(path_conv::clear_normalized_path): Ditto.
(path_conv::return_and_clear_normalized_path): Declare new method.