buf_pool_t: Remove n_frames, max_size, and blocks_of_frames.
The current buffer pool size is in curr_size.
buf_pool_init(): Remove parameter max_size.
buf_pool_get_max_size(), buf_pool_is_block(): Remove.
buf_block_align(): Do not assume that the buffer pool is allocated
in one chunk. Replace dependency on buf_pool->blocks_of_frames
with a call to buf_page_hash_get().
accessors returning pointers with macros that preserve const qualifiers.
In UNIV_DEBUG builds, retain the accessors and cast away constness there.
dfield_get_type(), dfield_get_data(), dtuple_get_nth_field(),
dict_table_get_nth_col(), dict_table_get_sys_col(): Implement as macro
unless #ifdef UNIV_DEBUG.
rec_get_nth_field(): Replace with rec_get_nth_field_offs() that does not
do pointer arithmetics. Implement rec_get_nth_field() as a macro.
