* search.c (Freplace_match): Adjust the match-data more
thoroughly when replacing strings in the buffer.
search.c (match-data): When INTEGERS is non-nil and the last match
was in a buffer, add the buffer as last element to the match data.
(Fset_match_data): If an additional element of the match-data is
a buffer, restore it to last_thing_searched.
(save_search_regs): Save last_thing_searched as part of the match
data.
(restore_match_data): Restore it again.