pgsql: Remove GUC_REPORT for new "server_version_num" GUC variable.

Log Message:
-----------
Remove GUC_REPORT for new "server_version_num" GUC variable. Added
overhead for every connection, per Tom.

Modified Files:
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pgsql/src/backend/utils/misc:
guc.c (r1.347 -> r1.348)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/guc.c.diff?r1=1.347&r2=1.348)