transactional SELECT and ALTER TABLE ...  REBUILD PARTITION".

Make open flags part of Open_table_context.
This allows to simplify some code and (in future)
enforce the invariant that we don't, say, request a back 
off on the table when there is MYSQL_OPEN_IGNORE_FLUSH 
flag.



sql/sql_base.cc:
  open_table() flags are part of Open_table_context.
  Remove dead code that would check for OPEN_VIEW_NO_PARSE,
  which is not an open table flag.
sql/sql_base.h:
  Move flags to Open_table_context. Reorder Open_table_context
  members to compact the structure footprint.
sql/sql_insert.cc:
  Update with a new calling signature of open_table().
sql/sql_table.cc:
  Update with a new calling signature of open_table().