pgsql: Disallow gssapi authentication on local connections, since it

Log Message:
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Disallow gssapi authentication on local connections, since it
requires a hostname to function.

Noted by Zdenek Kotala

Tags:
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REL8_4_STABLE

Modified Files:
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pgsql/src/backend/libpq:
hba.c (r1.188.2.3 -> r1.188.2.4)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/libpq/hba.c?r1=1.188.2.3&r2=1.188.2.4)