pgsql: Diagnose incompatible OpenLDAP versions during build and test.

Diagnose incompatible OpenLDAP versions during build and test.

With OpenLDAP versions 2.4.24 through 2.4.31, inclusive, PostgreSQL
backends can crash at exit.  Raise a warning during "configure" based on
the compile-time OpenLDAP version number, and test the crash scenario in
the dblink test suite.  Back-patch to 9.0 (all supported versions).

Branch
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master

Details
-------
http://git.postgresql.org/pg/commitdiff/d7cdf6ee36adeac9233678fb8f2a112e6678a770

Modified Files
--------------
configure                          |   52 ++++++++++++++++++++++++++++++++++++
configure.in                       |   29 ++++++++++++++++++++
contrib/dblink/Makefile            |    4 ++-
contrib/dblink/expected/.gitignore |    1 +
contrib/dblink/expected/dblink.out |   27 +++++++++++++++++++
contrib/dblink/input/paths.source  |   14 ++++++++++
contrib/dblink/output/paths.source |   11 ++++++++
contrib/dblink/pg_service.conf     |    7 +++++
contrib/dblink/sql/.gitignore      |    1 +
contrib/dblink/sql/dblink.sql      |   28 +++++++++++++++++++
src/test/regress/regress.c         |   43 +++++++++++++++++++++++++++++
11 files changed, 216 insertions(+), 1 deletion(-)