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, 5 insertions, 4 deletions

diff --git a/storage/sequence/sequence.cc b/storage/sequence/sequence.cc
index 8d9465f08c5..6a8625ce9b4 100644
--- a/storage/sequence/sequence.cc
+++ b/storage/sequence/sequence.cc
@@ -348,7 +348,9 @@ static int discover_table_existence(handlerton *hton, const char *db,
   return !parse_table_name(table_name, strlen(table_name), &from, &to, &step);
 }
 
-static int dummy_ret_int() { return 0; }
+static int dummy_commit_rollback(handlerton *, THD *, bool) { return 0; }
+
+static int dummy_savepoint(handlerton *, THD *, void *) { return 0; }
 
 /*****************************************************************************
   Example of a simple group by handler for queries like:
@@ -487,10 +489,9 @@ static int init(void *p)
   hton->create= create_handler;
   hton->discover_table= discover_table;
   hton->discover_table_existence= discover_table_existence;
-  hton->commit= hton->rollback=
-   (int (*)(handlerton *, THD *, bool)) &dummy_ret_int;
+  hton->commit= hton->rollback= dummy_commit_rollback;
   hton->savepoint_set= hton->savepoint_rollback= hton->savepoint_release=
-   (int  (*)(handlerton *, THD *, void *)) &dummy_ret_int;
+    dummy_savepoint;
   hton->create_group_by= create_group_by_handler;
   return 0;
 }