pgsql-server: Use dynamic buffer for token buffer in win32 admin check

Log Message:
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Use dynamic buffer for token buffer in win32 admin check

Magnus Hagander

Modified Files:
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pgsql-server/src/backend/port/win32:
security.c (r1.1 -> r1.2)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/port/win32/security.c.diff?r1=1.1&r2=1.2)