fix gcc 8 compiler warnings

There were two newly enabled warnings:
1. cast for a function pointers. Affected sql_analyse.h, mi_write.c
   and ma_write.cc, mf_iocache-t.cc, mysqlbinlog.cc, encryption.cc, etc

2. memcpy/memset of nontrivial structures. Fixed as:
* the warning disabled for InnoDB
* TABLE, TABLE_SHARE, and TABLE_LIST got a new method reset() which
  does the bzero(), which is safe for these classes, but any other
  bzero() will still cause a warning
* Table_scope_and_contents_source_st uses `TABLE_LIST *` (trivial)
  instead of `SQL_I_List<TABLE_LIST>` (not trivial) so it's safe to
  bzero now.
* added casts in debug_sync.cc and sql_select.cc (for JOIN)
* move assignment method for MDL_request instead of memcpy()
* PARTIAL_INDEX_INTERSECT_INFO::init() instead of bzero()
* remove constructor from READ_RECORD() to make it trivial
* replace some memcpy() with c++ copy assignments

1 files changed, 10 insertions, 0 deletions

diff --git a/sql/mdl.h b/sql/mdl.h
index 7961f1f24b2..15a1976876b 100644
--- a/sql/mdl.h
+++ b/sql/mdl.h
@@ -475,6 +475,16 @@ public:
     DBUG_ASSERT(ticket == NULL);
     type= type_arg;
   }
+  void move_from(MDL_request &from)
+  {
+    type= from.type;
+    duration= from.duration;
+    ticket= from.ticket;
+    next_in_list= from.next_in_list;
+    prev_in_list= from.prev_in_list;
+    key.mdl_key_init(&from.key);
+    from.ticket=  NULL; // that's what "move" means
+  }
 
   /*
     This is to work around the ugliness of TABLE_LIST