Fix handling of files removed during incremental dumps.

Fix handling of files removed during incremental dumps.

Changes to src/create.c and src/incremen.c are partially
based on patch from Alexander Peslyak <solar at openwall.com>.

The new testcases require paxutils commit f653a2b or later.

* src/common.h (struct name): New member `cmdline'.
(dump_file): Change type of the 2nd argument to bool.
(file_removed_diag, dir_removed_diag): New prototypes.
(addname): New argument `cmdline'.
(name_from_list): Change return value.
* src/create.c (dump_dir0, dump_dir): top_level is bool.
(create_archive): Update calls to name_from_list.
Take advantage of the name->cmdline to set top_level argument
during incremental backups.
(dump_file0): top_level is bool.
Do not bail out if a no-top-level file disappears during incremental
backup, use file_removed_diag instead.
(dump_filed): top_level is bool.
* src/incremen.c (update_parent_directory): Silently ignore
ENOENT.  It should have already been reported elsewhere.
(scan_directory): Use dir_removed_diag to report missing directories.
* src/misc.c (file_removed_diag, dir_removed_diag): New functions.
* src/names.c (name_gather): Set ->cmdname.
(addname): Likewise. All uses updated.
(name_from_list): Return struct name const *. All uses updated.

* tests/filerem01.at: New testcase.
* tests/filerem02.at: New testcase.
* tests/Makefile.am, tests/testsuite.at: Add filerem01.at, filerem02.at
* tests/grow.at, test/truncate.at: Use new syntax for genfile --run.

* NEWS: Update.
* doc/tar.texi: Minor fix.