dict_truncate_index_tree(): Add the parameter space for specifying the
new tablespace identifier of a single-table tablespace that has been
recreated.  When SYS_INDEXES.PAGE_NO == FIL_NULL, do not abort but
create the index tree.

fil_discard_tablespace(): Pass the return code from fil_delete_tablespace().

row_truncate_table_for_mysql(): Attempt to discard and recreate
single-table tablespaces.  Reassign the tablespace identifier both in
the data dictionary (SYS_TABLES and SYS_INDEXES) and in the data
dictionary cache.