and modify some functions to return const pointers. Add const qualifiers
to local variable declarations or casts to remove the const qualifier
in those places where write access is needed.
of clustered indexes. Previously, parts of the code assumed that these
columns would exist on all leaf pages. Simplify the update-in-place of
these columns.
Add inline function dict_index_is_clust() to replace all tests
index->type & DICT_CLUSTERED.
Remove the redo log entry types MLOG_ZIP_WRITE_TRX_ID and
MLOG_ZIP_WRITE_ROLL_PTR, because the modifications to these columns
are covered by logical logging.
Fuse page_zip_write_trx_id() and page_zip_write_roll_ptr() into
page_zip_write_trx_id_and_roll_ptr().
page_zip_dir_add_slot(), page_zip_available(): Add flag "is_clustered",
so that no space will be reserved for TRX_ID and ROLL_PTR on leaf pages
of secondary indexes.
page_zip_apply_log(): Flag an error when val==0 is encoded with two bytes.
page_zip_write_rec(): Add debug assertions that there is enough space
available for the entry before copying the data bytes of the record.
