reviewing patches

Hi,

I'll take care of those two patches (the former I did a review for the last
commitfest and the latter I'm interested in this new functionality). Objections?

EXPLAIN BUFFERS
https://commitfest.postgresql.org/action/patch_view?id=194

ProcessUtility_hook
https://commitfest.postgresql.org/action/patch_view?id=196


--
  Euler Taveira de Oliveira
  http://www.timbira.com/