[php-src] Issue #8281: mb_convert_encoding "\" (backslash) and "~" (tilde) convert failed to Shift_JIS

Issue: https://github.com/php/php-src/issues/8281 Comment Author: zonuexe @alexdowad I have presented these references as a separate source to show that there is more than one type of character set conversion map like [Japanese Shift-JIS Character Mapping - IBM Documentation](https://www.ibm.com/docs/en/cognos-analytics/10.2.2?topic=SSEP7J_10.2.2/com.ibm.swg.ba.cognos.ug_trnst.10.2.2.doc/c_appendix_round_trip_config.html). It seems that you have already implemented it based on the necessary knowledge. There may be little information available from these haystacks.