pgbouncer - pgbouncer: More magic cleanup, found even couple potential

Log Message:
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More magic cleanup, found even couple potential bugs.

- get_header() allowed < 5 length, which could trigger unsigned overflow.
- error from server when setting parameters did not do "return false"
- broken ParameterStatus should close connection.

Again, thanks to David Fetter who pushed for cleaner code.

Modified Files:
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    pgbouncer/src:
        admin.c (r1.15 -> r1.16)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgbouncer/pgbouncer/src/admin.c.diff?r1=1.15&r2=1.16)
        bouncer.h (r1.11 -> r1.12)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgbouncer/pgbouncer/src/bouncer.h.diff?r1=1.11&r2=1.12)
        client.c (r1.13 -> r1.14)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgbouncer/pgbouncer/src/client.c.diff?r1=1.13&r2=1.14)
        proto.c (r1.7 -> r1.8)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgbouncer/pgbouncer/src/proto.c.diff?r1=1.7&r2=1.8)
        server.c (r1.11 -> r1.12)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgbouncer/pgbouncer/src/server.c.diff?r1=1.11&r2=1.12)
        takeover.c (r1.4 -> r1.5)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgbouncer/pgbouncer/src/takeover.c.diff?r1=1.4&r2=1.5)