Backport BUG#38468 Memory leak detected when using mysqlbinlog utility

There were two memory leaks in mysqlbinlog command, one was already
fixed by previous patches, another one was that defaults_argv was
set to the value of argv after parse_args, in which called
handle_options after calling load_defaults and changed the value
of argv, and caused the memory allocated for defaults arguments
not freed.

Fixed the problem by setting defaults_argv right after calling
load_defaults.

client/mysqlbinlog.cc

@@ -1346,7 +1346,6 @@ static int parse_args(int *argc, char*** argv)
   int ho_error;
 
   result_file = stdout;
-  load_defaults("my",load_default_groups,argc,argv);
   if ((ho_error=handle_options(argc, argv, my_long_options, get_one_option)))
     exit(ho_error);
   if (debug_info_flag)
@@ -1998,8 +1997,9 @@ int main(int argc, char** argv)
 
   my_init_time(); // for time functions
 
+  load_defaults("my", load_default_groups, &argc, &argv);
+  defaults_argv= argv;
   parse_args(&argc, (char***)&argv);
-  defaults_argv=argv;
 
   if (!argc)
   {

mysql-test/t/mysqlbinlog.test

@@ -380,3 +380,27 @@ FLUSH LOGS;
 --echo End of 5.0 tests
 
 --echo End of 5.1 tests
+
+#
+# BUG#38468 Memory leak detected when using mysqlbinlog utility;
+#
+disable_query_log;
+RESET MASTER;
+CREATE TABLE t1 SELECT 1;
+FLUSH LOGS;
+DROP TABLE t1;
+enable_query_log;
+
+# Write an empty file for comparison
+write_file $MYSQLTEST_VARDIR/tmp/mysqlbinlog.warn.empty;
+EOF
+
+# Before fix of BUG#38468, this would generate some warnings
+--exec $MYSQL_BINLOG $MYSQLD_DATADIR/master-bin.000001 >/dev/null 2> $MYSQLTEST_VARDIR/tmp/mysqlbinlog.warn
+
+# Make sure the command above does not generate any error or warnings
+diff_files $MYSQLTEST_VARDIR/tmp/mysqlbinlog.warn $MYSQLTEST_VARDIR/tmp/mysqlbinlog.warn.empty;
+
+# Cleanup for this part of test
+remove_file $MYSQLTEST_VARDIR/tmp/mysqlbinlog.warn.empty;
+remove_file $MYSQLTEST_VARDIR/tmp/mysqlbinlog.warn;