Assert that pre/post-fix updated tuples are on the same page during replay.

If they were not 'oldtup.t_data' would be dereferenced while set to NULL
in case of a full page image for block 0.

Do so primarily to silence coverity; but also to make sure this prerequisite
isn't changed without adapting the replay routine as that would appear to
work in many cases.

Andres Freund
Use Size instead of uint32 to store result of sizeof()

Silences coverity and is more consistent with other functions in the
same file.

Andres Freund
Don't leak memory after connection aborts in pg_recvlogical.

Andres Freund, noticed by coverity.
Pass sensible value to memset() when randomizing reorderbuffer's tuple slab.

This is entirely harmless, but still wrong. Noticed by coverity.

Andres Freund