pgsql: Let installcheck-world pass against a server requiring a passwor

Let installcheck-world pass against a server requiring a password.

Give passwords to each user created in support of an ECPG connection
test case.  Use SET SESSION AUTHORIZATION, not a fresh connection, to
reduce privileges during a dblink test case.

To test against such a server, both the "make installcheck-world"
environment and the postmaster environment must provide the default
user's password; $PGPASSFILE is the principal way to do so.  (The
postmaster environment needs it for dblink and postgres_fdw tests.)

Branch
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master

Details
-------
http://git.postgresql.org/pg/commitdiff/c82725edfa1aec1cad940b15b6e22ee3dbd57f20

Modified Files
--------------
contrib/dblink/expected/dblink.out                 |    9 +--
contrib/dblink/sql/dblink.sql                      |    9 +--
src/interfaces/ecpg/test/connect/test5.pgc         |   18 +++--
src/interfaces/ecpg/test/expected/connect-test5.c  |   82 +++++++++++---------
.../ecpg/test/expected/connect-test5.stderr        |   18 +++--
5 files changed, 75 insertions(+), 61 deletions(-)