Ensure POSTGRES_HOME always overrides PATH.

[wdh]

Rebased TJC#30 onto nohuhu:improved-tests.

[wdh]

Test results with Postgres 9.4, 9.5 and 9.6:

[wdh@wdh Test-postgresql (make-POSTGRES_HOME-override-PATH)]$ POSTGRES_HOME=/usr/local/Cellar/postgresql\@9.4/9.4.17 prove -Ilib t/
t/00-base.t .............. ok
t/01-raii.t .............. 1/5 # PostgreSQL version: 9.4
t/01-raii.t .............. ok
t/02-multi.t ............. ok
t/04-multiprocess.t ...... ok
t/05-recycle-base-dir.t .. ok
t/06-unix-socket.t ....... ok
t/07-configs.t ........... ok
t/08-postgresql_conf.t ... ok
t/09-run_psql.t .......... ok
t/10-seed_scripts.t ...... ok
t/deadlock.t ............. 1/? # elapsed: 1
t/deadlock.t ............. ok
All tests successful.
Files=11, Tests=41, 76 wallclock secs ( 0.06 usr  0.03 sys + 23.77 cusr 15.14 csys = 39.00 CPU)
Result: PASS

[wdh@wdh Test-postgresql (make-POSTGRES_HOME-override-PATH)]$ POSTGRES_HOME=/usr/local/Cellar/postgresql\@9.5/9.5.12 prove -Ilib t/
t/00-base.t .............. ok
t/01-raii.t .............. 1/5 # PostgreSQL version: 9.5
t/01-raii.t .............. ok
t/02-multi.t ............. ok
t/04-multiprocess.t ...... ok
t/05-recycle-base-dir.t .. ok
t/06-unix-socket.t ....... ok
t/07-configs.t ........... ok
t/08-postgresql_conf.t ... ok
t/09-run_psql.t .......... ok
t/10-seed_scripts.t ...... ok
t/deadlock.t ............. 1/? # elapsed: 1
t/deadlock.t ............. ok
All tests successful.
Files=11, Tests=41, 70 wallclock secs ( 0.07 usr  0.03 sys + 21.57 cusr 12.61 csys = 34.28 CPU)
Result: PASS

[wdh@wdh Test-postgresql (make-POSTGRES_HOME-override-PATH)]$ POSTGRES_HOME=/usr/local/Cellar/postgresql\@9.6/9.6.8 prove -Ilib t/
t/00-base.t .............. ok
t/01-raii.t .............. 1/5 # PostgreSQL version: 9.6
t/01-raii.t .............. ok
t/02-multi.t ............. ok
t/04-multiprocess.t ...... ok
t/05-recycle-base-dir.t .. ok
t/06-unix-socket.t ....... ok
t/07-configs.t ........... ok
t/08-postgresql_conf.t ... ok
t/09-run_psql.t .......... ok
t/10-seed_scripts.t ...... ok
t/deadlock.t ............. 1/? # elapsed: 1
t/deadlock.t ............. ok
All tests successful.
Files=11, Tests=41, 63 wallclock secs ( 0.06 usr  0.03 sys + 18.59 cusr  9.14 csys = 27.82 CPU)
Result: PASS

[wdh]

Closed in favour of TJC#31