[parser] improve: GetAllCharsets and GetCharsetInfoByID (#247)
[parser] improve: GetAllCharsets and GetCharsetInfoByID (#247)


ngaut/tidb,pingcap/tidb,pingcap/tidb,pingcap/tidb,c4pt0r/tidb,pingcap/tidb,coocood/tidb,c4pt0r/tidb,kyle-wang/tidb,kyle-wang/tidb,c4pt0r/tidb,pingcap/tidb,ngaut/tidb,coocood/tidb,ngaut/tidb,kyle-wang/tidb,kyle-wang/tidb,pingcap/tidb,ngaut/tidb,ngaut/tidb,c4pt0r/tidb,kyle-wang/tidb,ngaut/tidb,c4pt0r/tidb,kyle-wang/tidb,c4pt0r/tidb