into -engines tree.

hander::table_share was not updated after changing table->s.


sql/ha_partition.cc:
  Valgrind warning after merge -main -> -engines, after bug#32943
  
  change_table_ptr can happen in a middle of
  alter table rename/drop/... partition
  
  the newly created partitions must get the updated table_share too.
sql/sql_base.cc:
  Bug#32943 was missing a call to change_table_ptr, this was found by valgrind
  after a merge from -main to -engines.