page_cur_search_with_match() could avoid rec_get_offsets()

While working on MDEV-35049, I noticed that the function page_cur_search_with_match() is allocating memory for invoking rec_get_offsets(). Its callers typically allocate this memory as well, and they would also invoke rec_get_offsets() again on the returned record. This could be optimized in some way.

A possible fix might be to implement a comparison function that would compute the addresses of fields of records on the fly.