Improve checks for incompatible options.

* src/common.h (READ_LIKE_SUBCOMMAND): Remove define.
* src/tar.c (IS_SUBCOMMAND_CLASS): New macro.
(decode_options): Use IS_SUBCOMMAND_CLASS in checking
option compatibility.
Accept the --verify option only with subcommands that
write to the archive.

* tests/opcomp01.at: New test case.
* tests/opcomp02.at: New test case.
* tests/opcomp03.at: New test case.
* tests/opcomp04.at: New test case.
* tests/opcomp05.at: New test case.
* tests/opcomp06.at: New test case.
* tests/Makefile.am: Add new testcases.
* tests/testsuite.at: Likewise.