RFR: 8254965: Remove unused Matcher::_ruleName and make ruleName non-product

[Vladimir Kozlov]

On Sun, 18 Oct 2020 09:22:45 GMT, Claes Redestad <redestad at openjdk.org> wrote:

> - Matcher::_ruleName is unused - remove
> - ruleName, defined via ad, is only used by a non-product routine. #ifdef it accordingly
> 
> This reduces the JVM size (-63Kb on linux-x64, or about 0.25%)

Unfortunately we may soon use it (problem was found only in product VM during Graal testing). Following JDK-8247350 fix
to catch issues in product VM we may want to use rule names:

        tty->print_cr("fatal error context information: rule: (%s) n_size (%d), current_offset (%d), instr_offset (%d)",
        mach->rule() == 9999999 ? "<unknown>" : ruleName[mach->rule()], n_size, current_offset, instr_offset);

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PR: https://git.openjdk.java.net/jdk/pull/722