pgsql: Report all dependent objects to the server log when a shared

Log Message:
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Report all dependent objects to the server log when a shared object is dropped,
and only a truncated log of the objects in the current database to the client.
Also, instead of reporting object counts for all databases on which the user
might own objects, report only as many as fit in the predefined line count.

This is to avoid flooding the client when the user owns too many objects,
which could cause problems.

Per report from Ed L. on April 4th and subsequent discussion.

Modified Files:
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    pgsql/src/backend/catalog:
        pg_shdepend.c (r1.18 -> r1.19)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/pg_shdepend.c.diff?r1=1.18&r2=1.19)