b-tree cursor functions to the buffer pool requests, in order to make
the latch diagnostics more accurate.

buf_page_optimistic_get_func(): Renamed to buf_page_optimistic_get().

btr_page_get_father_node_ptr(), btr_insert_on_non_leaf_level(),
btr_pcur_open(), btr_pcur_open_with_no_init(), btr_pcur_open_on_user_rec(),
btr_pcur_open_at_rnd_pos(), btr_pcur_restore_position(),
btr_cur_open_at_index_side(), btr_cur_open_at_rnd_pos():
Rename the function to _func and add the parameters file, line.
Define wrapper macros with __FILE__, __LINE__.

btr_cur_search_to_nth_level(): Add the parameters file, line.