fts_is_charset_cjk(): Do not call strcmp()

Remove a bogus reference to gb18030_chinese_ci, which was introduced
in MySQL 5.7. It is roughly equivalent to utf8mb4_unicode_ci, just
using a different internal encoding, and different collation.

storage/innobase/include/fts0types.ic

@@ -1,6 +1,7 @@
 /*****************************************************************************
 
 Copyright (c) 2007, 2015, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 2017, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -115,19 +116,14 @@ bool
 fts_is_charset_cjk(
 	const CHARSET_INFO*	cs)
 {
-	if (strcmp(cs->name, "gb2312_chinese_ci") == 0
-	    || strcmp(cs->name, "gbk_chinese_ci") == 0
-	    || strcmp(cs->name, "big5_chinese_ci") == 0
-	    || strcmp(cs->name, "gb18030_chinese_ci") == 0
-	    || strcmp(cs->name, "ujis_japanese_ci") == 0
-	    || strcmp(cs->name, "sjis_japanese_ci") == 0
-	    || strcmp(cs->name, "cp932_japanese_ci") == 0
-	    || strcmp(cs->name, "eucjpms_japanese_ci") == 0
-	    || strcmp(cs->name, "euckr_korean_ci") == 0) {
-		return(true);
-	} else {
-		return(false);
-	}
+	return cs == &my_charset_gb2312_chinese_ci
+		|| cs == &my_charset_gbk_chinese_ci
+		|| cs == &my_charset_big5_chinese_ci
+		|| cs == &my_charset_ujis_japanese_ci
+		|| cs == &my_charset_sjis_japanese_ci
+		|| cs == &my_charset_cp932_japanese_ci
+		|| cs == &my_charset_eucjpms_japanese_ci
+		|| cs == &my_charset_euckr_korean_ci;
 }
 
 /** Select the FTS auxiliary index for the given character by range.