Unused macros in contrib code

While doing some archaeology I came across a couple of macros in pgstattuple
and pageinspect contrib code which seems to have been unused for some time.
CHECK_PAGE_OFFSET_RANGE is unused in both modules and commit 6405842 which
introduced contrib/pageinspect moved the code making CHECK_RELATION_BLOCK_RANGE
in pgstattuple unused.

For cleanliness sake it seems reasonable to remove these, patch attached which
passes make check (regular and in contrib).

cheers ./daniel