We already install assorted tools for testing extensions, but these two
were missing.  Having them installed, and after ISOLATION support was
added to PGXS's  makefiles by d3c09b9b, helps third-party modules
usefully include isolation tests.  Compare c3a08184.

Author: Craig Ringer <craig.ringer@enterprisedb.com>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/CAMsr+YFsCMH3B4uOPFE+2qWM6k=o=hf9LGiPNCfwqKdUPz_BsQ@mail.gmail.com