Handle errors returned by system crypt() in ENCRYPT(). (Bug #13619)

mysql-test/r/func_crypt.result:
  Add new results
mysql-test/t/func_crypt.test:
  Add new regression test
sql/item_strfunc.cc:
  Handle NULL result from call to crypt().

mysql-test/r/func_crypt.result

@@ -92,3 +92,6 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
 Warnings:
 Note	1003	select password(_latin1'idkfa ') AS `password('idkfa ')`,old_password(_latin1'idkfa') AS `old_password('idkfa')`
+select encrypt('1234','_.');
+encrypt('1234','_.')
+#

mysql-test/t/func_crypt.test

@@ -49,4 +49,10 @@ select old_password(' i 	 d k f a ');
 
 explain extended select password('idkfa '), old_password('idkfa');
 
+#
+# Bug #13619: Crash on FreeBSD with salt like '_.'
+#
+--replace_column 1 #
+select encrypt('1234','_.');
+
 # End of 4.1 tests

sql/item_strfunc.cc

@@ -1497,7 +1497,13 @@ String *Item_func_encrypt::val_str(String *str)
     salt_ptr= salt_str->c_ptr();
   }
   pthread_mutex_lock(&LOCK_crypt);
-  char *tmp=crypt(res->c_ptr(),salt_ptr);
+  char *tmp= crypt(res->c_ptr(),salt_ptr);
+  if (!tmp)
+  {
+    pthread_mutex_unlock(&LOCK_crypt);
+    null_value= 1;
+    return 0;
+  }
   str->set(tmp,(uint) strlen(tmp),res->charset());
   str->copy();
   pthread_mutex_unlock(&LOCK_crypt);