On 9.4 you can't run 'make check' since we don't have any way to make a temp
instance using PGXS. So you'll need to roll a 9.4 install yourself, with
something like:

export PATH=$HOME/pg/94/bin:$PATH
export PGUSER=postgres

[ -e 94test ] && pg_ctl -D 94test -m immediate -w stop
rm -rf 94test
initdb -D 94test -U postgres -A trust
grep -v '^track_commit_timestamp' regress-postgresql.conf >> 94test/postgresql.conf
cp regress-pg_hba.conf 94test/
PGPORT=5495 pg_ctl -D 94test -w -l 94test.log start
PGPORT=5495 make -s clean install installcheck
