pgsql: Obstruct shell, SQL, and conninfo injection via database and rol

Obstruct shell, SQL, and conninfo injection via database and role names.

Due to simplistic quoting and confusion of database names with conninfo
strings, roles with the CREATEDB or CREATEROLE option could escalate to
superuser privileges when a superuser next ran certain maintenance
commands.  The new coding rule for PQconnectdbParams() calls, documented
at conninfo_array_parse(), is to pass expand_dbname=true and wrap
literal database names in a trivial connection string.  Escape
zero-length values in appendConnStrVal().  Back-patch to 9.1 (all
supported versions).

Nathan Bossart, Michael Paquier, and Noah Misch.  Reviewed by Peter
Eisentraut.  Reported by Nathan Bossart.

Security: CVE-2016-5424

Branch
------
REL9_4_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/254eb04f17b8c0a933ff0cdf2003339a460d778f

Modified Files
--------------
contrib/pg_upgrade/check.c           |  18 ++--
contrib/pg_upgrade/dump.c            |  15 ++-
contrib/pg_upgrade/pg_upgrade.c      |  15 ++-
contrib/pg_upgrade/pg_upgrade.h      |   4 +
contrib/pg_upgrade/server.c          |  50 +++++----
contrib/pg_upgrade/test.sh           |  17 +++
contrib/pg_upgrade/util.c            | 204 +++++++++++++++++++++++++++++++++++
contrib/pg_upgrade/version.c         |  10 +-
contrib/pg_upgrade/version_old_8_3.c |  34 ++++--
src/bin/pg_basebackup/streamutil.c   |  12 ++-
src/bin/pg_dump/dumputils.c          | 204 +++++++++++++++++++++++++++++++++++
src/bin/pg_dump/dumputils.h          |   3 +
src/bin/pg_dump/pg_backup.h          |   2 +-
src/bin/pg_dump/pg_backup_archiver.c |  34 ++++--
src/bin/pg_dump/pg_backup_db.c       |   9 +-
src/bin/pg_dump/pg_dumpall.c         | 162 +++-------------------------
src/bin/psql/command.c               |  15 ++-
src/bin/scripts/clusterdb.c          |   9 +-
src/bin/scripts/reindexdb.c          |  14 ++-
src/bin/scripts/vacuumdb.c           |  12 ++-
src/interfaces/libpq/fe-connect.c    |   6 +-
src/tools/msvc/vcregress.pl          |  41 +++++++
22 files changed, 680 insertions(+), 210 deletions(-)