pgsql: Add a boolean GUC parameter "bonjour" to control whether a

Log Message:
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Add a boolean GUC parameter "bonjour" to control whether a Bonjour-enabled
build actually attempts to advertise itself via Bonjour. Formerly it always
did so, which meant that packagers had to decide for their users whether
this behavior was wanted or not. The default is "off" to be on the safe
side, though this represents a change in the default behavior of a
Bonjour-enabled build. Per discussion.

Modified Files:
--------------
pgsql/doc/src/sgml:
config.sgml (r1.224 -> r1.225)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/config.sgml?r1=1.224&r2=1.225)
pgsql/src/backend/postmaster:
postmaster.c (r1.595 -> r1.596)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/postmaster.c?r1=1.595&r2=1.596)
pgsql/src/backend/utils/misc:
guc.c (r1.515 -> r1.516)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/guc.c?r1=1.515&r2=1.516)
postgresql.conf.sample (r1.264 -> r1.265)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/postgresql.conf.sample?r1=1.264&r2=1.265)
pgsql/src/include/postmaster:
postmaster.h (r1.20 -> r1.21)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/postmaster/postmaster.h?r1=1.20&r2=1.21)