varint - varint: refactor operations on VarInts to functions with normal

Log Message:
-----------
refactor operations on VarInts to functions with normal C apis, to make them easier to call from other VarInt
operations(avoiding DirectFunctionCallX).  Add modulus and divmod functions. 

Modified Files:
--------------
    varint:
        Makefile (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/varint/varint/Makefile.diff?r1=1.2&r2=1.3)
        uninstall_varint.sql (r1.1 -> r1.2)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/varint/varint/uninstall_varint.sql.diff?r1=1.1&r2=1.2)
        varint.c (r1.4 -> r1.5)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/varint/varint/varint.c.diff?r1=1.4&r2=1.5)
        varint.h (r1.4 -> r1.5)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/varint/varint/varint.h.diff?r1=1.4&r2=1.5)
        varint.sql.in (r1.4 -> r1.5)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/varint/varint/varint.sql.in.diff?r1=1.4&r2=1.5)
    varint/expected:
        division.out (r1.1 -> r1.2)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/varint/varint/expected/division.out.diff?r1=1.1&r2=1.2)
        multiplication.out (r1.1 -> r1.2)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/varint/varint/expected/multiplication.out.diff?r1=1.1&r2=1.2)
        subtraction.out (r1.1 -> r1.2)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/varint/varint/expected/subtraction.out.diff?r1=1.1&r2=1.2)
    varint/sql:
        division.sql (r1.1 -> r1.2)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/varint/varint/sql/division.sql.diff?r1=1.1&r2=1.2)
        subtraction.sql (r1.1 -> r1.2)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/varint/varint/sql/subtraction.sql.diff?r1=1.1&r2=1.2)

Added Files:
-----------
    varint:
        varint_core.c (r1.1)

(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/varint/varint/varint_core.c?rev=1.1&content-type=text/x-cvsweb-markup)
        varint_core.h (r1.1)

(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/varint/varint/varint_core.h?rev=1.1&content-type=text/x-cvsweb-markup)