pgsql: Add auto-explain contrib module for automatic logging of the

Log Message:
-----------
Add auto-explain contrib module for automatic logging of the plans of
slow-running queries.

Takahiro Itagaki

Modified Files:
--------------
    pgsql/contrib:
        Makefile (r1.84 -> r1.85)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/Makefile?r1=1.84&r2=1.85)
        README (r1.97 -> r1.98)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/README?r1=1.97&r2=1.98)
    pgsql/doc/src/sgml:
        contrib.sgml (r1.9 -> r1.10)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/contrib.sgml?r1=1.9&r2=1.10)
        filelist.sgml (r1.57 -> r1.58)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/filelist.sgml?r1=1.57&r2=1.58)

Added Files:
-----------
    pgsql/contrib/auto_explain:
        Makefile (r1.1)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/auto_explain/Makefile?rev=1.1&content-type=text/x-cvsweb-markup)
        auto_explain.c (r1.1)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/auto_explain/auto_explain.c?rev=1.1&content-type=text/x-cvsweb-markup)
    pgsql/doc/src/sgml:
        auto-explain.sgml (r1.1)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/auto-explain.sgml?rev=1.1&content-type=text/x-cvsweb-markup)