Bug#50373 --secure-file-priv=""

Correcting a patch misstake. The converted file path is placed in 'buff' not in opt_secure_file_priv.

mysql-test/r/loaddata.result:
  * Updated test case; Since secure_file_priv now is normalized the previous values are changed.
sql/mysqld.cc:
  * Fixed patch misstake

mysql-test/r/loaddata.result

@@ -204,10 +204,10 @@ a	b	c
 15	NULL	Fifteen
 show variables like "secure_file_pri%";
 Variable_name	Value
-secure_file_priv	MYSQLTEST_VARDIR/
+secure_file_priv	MYSQLTEST_VARDIR
 select @@secure_file_priv;
 @@secure_file_priv
-MYSQLTEST_VARDIR/
+MYSQLTEST_VARDIR
 set @@secure_file_priv= 0;
 ERROR HY000: Variable 'secure_file_priv' is a read only variable
 truncate table t1;

sql/mysqld.cc

@@ -8846,7 +8846,7 @@ static int fix_paths(void)
       convert_dirname(buff, opt_secure_file_priv, NullS);
       char *secure_file_real_path= (char *)my_malloc(FN_REFLEN, MYF(MY_FAE));
       if (secure_file_real_path == 0 ||
-          my_realpath(secure_file_real_path, opt_secure_file_priv, 0))
+          my_realpath(secure_file_real_path, buff, 0))
       {
         sql_print_warning("Failed to normalize the argument for --secure-file-priv.");
         return 1;