BUG#30996: Committed too early when autocommit and lock table

Moved out a lot of code into functions from external_lock and
start_stmt
Fixed a crashing bug at memory alloc failure
Merged the stmt and all variables into one trans variable
Always register start of statement as according to the
interface of the handlers.
Also register for start of transaction when not statement commit
== not autocommit AND no begin - commit ongoing
Now that we registered in a proper manner we also needed to handle
the commit call when end of statement and transaction is ongoing
Added start_stmt_count to know when we have start of statement
for first table

mysql-test/suite/ndb/r/ndb_lock_table.result

+drop table if exists t1;
+create table t1 (a int) engine ndb;
+set autocommit=1;
+lock table t1 write;
+set autocommit=0;
+insert into t1 values (0);
+rollback;
+select * from t1;
+a
+unlock tables;
+drop table t1;

mysql-test/suite/ndb/t/ndb_lock_table.test

+-- source include/have_ndb.inc
+
+# BUG 30996
+--disable_warnings
+drop table if exists t1;
+--enable_warnings
+create table t1 (a int) engine ndb;
+set autocommit=1;
+lock table t1 write;
+set autocommit=0;
+insert into t1 values (0);
+rollback;
+select * from t1;
+unlock tables;
+drop table t1;

sql/ha_ndbcluster.h

@@ -204,8 +204,8 @@ class Thd_ndb
   Ndb *ndb;
   ulong count;
   uint lock_count;
-  NdbTransaction *all;
-  NdbTransaction *stmt;
+  uint start_stmt_count;
+  NdbTransaction *trans;
   bool m_error;
   bool m_slow_path;
   int m_error_code;
@@ -496,6 +496,10 @@ static void set_tabname(const char *pathname, char *tabname);
   friend int execute_no_commit(ha_ndbcluster*, NdbTransaction*, bool);
   friend int execute_no_commit_ie(ha_ndbcluster*, NdbTransaction*, bool);
 
+  void transaction_checks(THD *thd);
+  int start_statement(THD *thd, Thd_ndb *thd_ndb, Ndb* ndb);
+  int init_handler_for_statement(THD *thd, Thd_ndb *thd_ndb);
+
   NdbTransaction *m_active_trans;
   NdbScanOperation *m_active_cursor;
   const NdbDictionary::Table *m_table;