pgsql: Put flex'ed and bison'ed files in contrib in the distribution

Log Message:
-----------
Put flex'ed and bison'ed files in contrib in the distribution tarball, as
is done for the analogous files in the main distribution.

Modified Files:
--------------
    pgsql:
        GNUmakefile.in (r1.42 -> r1.43)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/GNUmakefile.in.diff?r1=1.42&r2=1.43)
    pgsql/contrib:
        Makefile (r1.63 -> r1.64)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/Makefile.diff?r1=1.63&r2=1.64)
    pgsql/contrib/cube:
        Makefile (r1.17 -> r1.18)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/cube/Makefile.diff?r1=1.17&r2=1.18)
    pgsql/contrib/seg:
        Makefile (r1.16 -> r1.17)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/seg/Makefile.diff?r1=1.16&r2=1.17)

Added Files:
-----------
    pgsql/contrib/cube:
        .cvsignore (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/cube/.cvsignore?rev=1.1&content-type=text/x-cvsweb-markup)
    pgsql/contrib/seg:
        .cvsignore (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/seg/.cvsignore?rev=1.1&content-type=text/x-cvsweb-markup)