compressed pages.
btr_root_raise_and_insert(): Distinguish root_page_zip and new_page_zip.
btr_cur_set_ownership_of_extern_field(): Do not log the write on the
uncompressed page if it will be logged for page_zip.
lock_rec_insert_check_and_lock(), lock_sec_rec_modify_check_and_lock():
Update the max_trx_id field also on the compressed page.
mlog_write_ulint(): Add UNIV_UNLIKELY hints. Remove trailing white space.
mlog_log_string(): Remove trailing white space.
rec_set_field_extern_bits(): Remove parameter mtr, as the write will either
occur in the heap, or it will be logged at a higher level.
recv_parse_or_apply_log_rec_body(),
page_zip_write_header(): Add log record type MLOG_ZIP_WRITE_HEADER.
page_header_set_field(): Pass mtr=NULL to page_zip_write_header().
page_header_reset_last_insert(): Pass mtr to page_zip_write_header().
btr_page_set_index_id(), btr_page_set_level(),
btr_page_set_next(), btr_page_set_prev(): Pass mtr to page_zip_write_header().
row_upd_rec_sys_fields(): Pass mtr=NULL to page_zip_write_trx_id() and
page_zip_write_roll_ptr(), since the write will be logged at a higher level.
page_zip_write_header(): Add parameter mtr.
page_zip_write_header_log(): New function.
Remove rec_set_nth_field_extern_bit().
Make rec_set_nth_field_extern_bit_old() static.
Rename rec_set_nth_field_extern_bit_new()
to rec_set_field_extern_bits_new() and make it static.
row_ins_index_entry_low(): Remove bogus TODO comment.
This has not been extensively tested yet, because some other part of the
code breaks in "ibtestblob".
btr_free_page_low(): Add parameters "space" and "page_no", because they
are omitted from compressed BLOB pages.
btr0cur.c: Implement the compression and decompression of BLOB columns,
enabled at compile-time (#define ZIP_BLOB TRUE) for now.
btr_rec_free_externally_stored_fields(),
btr_copy_externally_stored_field(): Made static
mlog_log_string(): New function, split from mlog_write_string(), allows
to avoid a dummy memcpy() of compressed BLOB pages.
