MDEV-15563: Fix cmake -DPLUGIN_PERFSCHEMA=NO

Commit 22feb179 broke the build
with performance_schema disabled.

dict_col_t::same_charset(): An auxiliary function to
dict_col_t::same_format(). Determine if two non-binary string
columns have the same character set.

storage/innobase/data/data0type.cc

 /*****************************************************************************
 
 Copyright (c) 1996, 2015, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2017, 2018, MariaDB Corporation.
+Copyright (c) 2017, 2019, 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
@@ -24,7 +24,8 @@ Data types
 Created 1/16/1996 Heikki Tuuri
 *******************************************************/
 
-#include "data0type.h"
+#include "dict0mem.h"
+#include "my_sys.h"
 
 /** The DB_TRX_ID,DB_ROLL_PTR values for "no history is available" */
 const byte reset_trx_id[DATA_TRX_ID_LEN + DATA_ROLL_PTR_LEN] = {
@@ -160,6 +161,22 @@ dtype_validate(
 	return(TRUE);
 }
 
+bool dict_col_t::same_charset(const dict_col_t& other) const
+{
+	if (dtype_is_non_binary_string_type(mtype, prtype)
+	    && dtype_is_non_binary_string_type(other.mtype, other.prtype)) {
+		uint csn1 = (uint) dtype_get_charset_coll(prtype);
+		uint csn2 = (uint) dtype_get_charset_coll(other.prtype);
+		CHARSET_INFO* cs1 = get_charset(csn1, MYF(MY_WME));
+		CHARSET_INFO* cs2 = get_charset(csn2, MYF(MY_WME));
+		if (!my_charset_same(cs1, cs2)) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
 #ifdef UNIV_DEBUG
 /** Print a data type structure.
 @param[in]	type	data type */

storage/innobase/include/dict0mem.h

@@ -682,6 +682,12 @@ struct dict_col_t{
 		def_val.data = NULL;
 	}
 
+private:
+	/** Determine if the columns have the same character set
+	@param[in]	other	column to compare to
+	@return	whether the columns have the same character set */
+	bool same_charset(const dict_col_t& other) const;
+public:
 	/** Determine if the columns have the same format
 	except for is_nullable() and is_versioned().
 	@param[in]	other	column to compare to
@@ -694,17 +700,6 @@ struct dict_col_t{
 		    || mbmaxlen != other.mbmaxlen) {
 			return false;
 		}
-		if (dtype_is_non_binary_string_type(mtype, prtype)
-		    && dtype_is_non_binary_string_type(other.mtype,
-						       other.prtype)) {
-			uint csn1 = (uint) dtype_get_charset_coll(prtype);
-			uint csn2 = (uint) dtype_get_charset_coll(other.prtype);
-			CHARSET_INFO* cs1 = get_charset(csn1, MYF(MY_WME));
-			CHARSET_INFO* cs2 = get_charset(csn2, MYF(MY_WME));
-			if (!my_charset_same(cs1, cs2)) {
-				return false;
-			}
-		}
 
 		if (!((prtype ^ other.prtype)
 		      & ~(DATA_NOT_NULL | DATA_VERSIONED))) {
@@ -717,14 +712,16 @@ struct dict_col_t{
 			case DATA_MYSQL:
 			case DATA_VARCHAR:
 			case DATA_VARMYSQL:
-				return mtype == DATA_CHAR
+				return (mtype == DATA_CHAR
 					|| mtype == DATA_MYSQL
 					|| mtype == DATA_VARCHAR
-					|| mtype == DATA_VARMYSQL;
+					|| mtype == DATA_VARMYSQL)
+					&& same_charset(other);
 			case DATA_FIXBINARY:
 			case DATA_BINARY:
-				return mtype == DATA_FIXBINARY
-					|| mtype == DATA_BINARY;
+				return (mtype == DATA_FIXBINARY
+					|| mtype == DATA_BINARY)
+					&& same_charset(other);
 			case DATA_INT:
 				return mtype == DATA_INT;
 			}