from branches/zip.

btr_cur_optimistic_delete(): Split a too long line in the way it is
split in branches/zip.

buf_page_get_gen(): Add missing space in the function comment.

buf_print_io(): Restoer a removed space to the printout.

univ.i: Remove C++-style (or C99-style) comments.

buf0buf.h: Undo the white-space changes to the wrapper macros of
buf_page_get_gen().

ibuf_update_free_bits_low(): Revert the changes.  Restore the assertion
that this function must not be invoked on compressed pages.  The function
ibuf_update_free_bits_zip() is for compressed pages.

ibuf_insert_to_index_page(): Undo a white-space change.