Fix hard links recognition with -c --remove-files

* src/create.c (dump_hard_link): Always look up in the link table
if remove_files_option is set. Patch suggested by Theodore Ts'o
<tytso@mit.edu>.
(check_links): Remove extra newline from the warning message.
* tests/link02.at, tests/link03.at: New testcases.
* tests/Makefile.am (TESTSUITE_AT): Add link02.at and link03.at
* tests/testsuite.at: Include link02.at and link03.at