BUG#16068: Plugin related bugs

Fixed that --plugin_dir option doesn't work.
Fixed that parser name is not restored correctly from the table.

sql/mysqld.cc

@@ -7448,10 +7448,9 @@ static void fix_paths(void)
   (void) my_load_path(mysql_home,mysql_home,""); // Resolve current dir
   (void) my_load_path(mysql_real_data_home,mysql_real_data_home,mysql_home);
   (void) my_load_path(pidfile_name,pidfile_name,mysql_real_data_home);
-  strmake(opt_plugin_dir, get_relative_path(LIBDIR),
-          sizeof(opt_plugin_dir) - 1);
+  (void) my_load_path(opt_plugin_dir, opt_plugin_dir_ptr ? opt_plugin_dir_ptr :
+                                      get_relative_path(LIBDIR), mysql_home);
   opt_plugin_dir_ptr= opt_plugin_dir;
-  (void) my_load_path(opt_plugin_dir, opt_plugin_dir_ptr, mysql_home);
 
   char *sharedir=get_relative_path(SHAREDIR);
   if (test_if_hard_path(sharedir))

sql/table.cc

@@ -538,7 +538,7 @@ static int open_binary_frm(THD *thd, TABLE_SHARE *share, uchar *head,
 #endif
       next_chunk+= str_db_type_length + 2;
     }
-    if (next_chunk + 4 < buff_end)
+    if (next_chunk + 5 < buff_end)
     {
       uint32 partition_info_len = uint4korr(next_chunk);
 #ifdef WITH_PARTITION_STORAGE_ENGINE
@@ -561,7 +561,7 @@ static int open_binary_frm(THD *thd, TABLE_SHARE *share, uchar *head,
         goto err;
       }
 #endif
-      next_chunk+= 4 + partition_info_len;
+      next_chunk+= 5 + partition_info_len;
     }
     keyinfo= share->key_info;
     for (i= 0; i < keys; i++, keyinfo++)