Update for new exclude module from gnulib. Add testcases by Phil Proudman.

Update for new exclude module from gnulib. Add testcases by Phil Proudman.

* src/names.c (is_pattern): Remove.
(regex_usage_warning): Use fnmatch_pattern_has_wildcards instead of
is_pattern.
* src/tar.c: New option --exclude-backups.
(vcs_file_table, backup_file_table): New globals.
(add_exclude_array): New function.
* tests/exclude01.at, tests/exclude02.at,
tests/exclude03.at, tests/exclude04.at,
tests/exclude05.at: New testcases. Supplied by Phil Proudman.
* tests/Makefile.am (TESTSUITE_AT): Add new tests.
* tests/testsuite.at: Add new tests.
* THANKS: Update.