be set always.
trx_rollback_active(): Split from trx_rollback_or_clean_all_without_sess().
row_undo_dictionary(): Do not return a value. Assert that all operations
succeed.
row_merge_drop_index(): Remove bogus comment about void return value.
trx_dummy_sess: Move the declaration from trx0roll.h to trx0trx.h,
because the variable is defined in trx0trx.c.
buf_page_get_gen(). This saves one mutex operation per block request.
buf_page_get_gen(), various macros and functions: Add parameter zip_size.
btr_node_ptr_get_child(): Add parameter index.
fil_space_get_latch(): Add optional output parameter zip_size.
fil_space_get_zip_size(): Return 0 for space id==0, because the
system tablespace is never compressed.
fsp_header_init(): Remove the parameter zip_size.
ibuf_free_excess_pages(): Remove the parameter zip_size.
trx_rseg_t, trx_undo_t: Add field zip_size.
xdes_lst_get_next(): Remove, unused.
with page_get_page_no() and page_get_space_id(). We want to avoid
buf_block_align() calls, and the page_no and space_id are now stamped
on the pages early on.
