Adding LOAD DATA tests for MDEV-11079 and MDEV-11631

c3cf7f47 reverted the patch
for BUG#24487120. After merging the reverting patch from MySQL
to MariaDB the problems described in MDEV-11079 and MDEV-11631 disappeared.
Adding test cases only.

mysql-test/r/loaddata.result

@@ -532,3 +532,21 @@ FIELDS TERMINATED BY 't' LINES TERMINATED BY '';
 Got one of the listed errors
 SET @@sql_mode= @old_mode;
 DROP TABLE t1;
+#
+# MDEV-11079 Regression: LOAD DATA INFILE lost BLOB support using utf8 load files
+#
+CREATE TABLE t1 (a mediumblob NOT NULL) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci;
+LOAD DATA INFILE '../../std_data/loaddata/mdev-11079.txt' INTO TABLE t1 CHARSET utf8 FIELDS TERMINATED BY ';' ENCLOSED BY '"' ESCAPED BY '\\' LINES TERMINATED BY '\n';
+SELECT HEX(a) FROM t1;
+HEX(a)
+25AAABAC
+DROP TABLE t1;
+#
+# MDEV-11631 LOAD DATA INFILE fails to load data with an escape character followed by a multi-byte character
+#
+CREATE TABLE t1 (a VARCHAR(10) CHARACTER SET utf8);
+LOAD DATA INFILE '../../std_data/loaddata/mdev-11631.txt' INTO TABLE t1 CHARACTER SET utf8;
+SELECT HEX(a) FROM t1;
+HEX(a)
+C3A4
+DROP TABLE t1;

mysql-test/std_data/loaddata/mdev-11079.txt

+"%"

mysql-test/std_data/loaddata/mdev-11631.txt

+\ä

mysql-test/t/loaddata.test

@@ -658,3 +658,21 @@ SET @@sql_mode= @old_mode;
 --remove_file $MYSQLTEST_VARDIR/mysql
 DROP TABLE t1;
 
+
+--echo #
+--echo # MDEV-11079 Regression: LOAD DATA INFILE lost BLOB support using utf8 load files
+--echo #
+
+CREATE TABLE t1 (a mediumblob NOT NULL) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci;
+LOAD DATA INFILE '../../std_data/loaddata/mdev-11079.txt' INTO TABLE t1 CHARSET utf8 FIELDS TERMINATED BY ';' ENCLOSED BY '"' ESCAPED BY '\\' LINES TERMINATED BY '\n';
+SELECT HEX(a) FROM t1;
+DROP TABLE t1;
+
+--echo #
+--echo # MDEV-11631 LOAD DATA INFILE fails to load data with an escape character followed by a multi-byte character
+--echo #
+
+CREATE TABLE t1 (a VARCHAR(10) CHARACTER SET utf8);
+LOAD DATA INFILE '../../std_data/loaddata/mdev-11631.txt' INTO TABLE t1 CHARACTER SET utf8;
+SELECT HEX(a) FROM t1;
+DROP TABLE t1;