Update mysqldump to dump the needed tablespaces to create the tables
for either the dbs or tables we're dumping.

With --all-tablespaces, we still dump everything.


client/mysqldump.c:
  Add --no-tablespaces to force not dumping any tablespace information
  
  Change behaviour so that:
  If dumping all databases, all tablespaces are dumped
  If dumping with --all-tablespaces, all tablespaces are dumped
  If dumping a set of databases, dump only tablespaces used by tables in that database
  If dumping a set of tables, dump only tablespaces used by those tables
  
  If --no-tablespaces is specified, no tablespaces are dumped.
  
  Default behaviour is to dump a restorable dump - i.e. with the tablespaces.
  
  When connecting to old mysqld, --no-tablespaces should be specified.
sql/sql_show.cc:
  Use the TABLESPACE_NAME field of the INFORMATION_SCHEMA.PARTITIONS table.
  
  NOTE: *CHANGE* in behaviour: if no tablespace, TABLESPACE_NAME will be NULL.
  This is to support a tablespace called 'default' (which you can happily create).
  
  It is likely that the other fields with 'default' should change too.
  
  This should also happily continue to work in the future (from a user point of view)
  when we introduce tablespace per partition.