pg-migrator - src: Use assert rather than Assert because we don't link

Log Message:
-----------
Use assert rather than Assert because we don't link to the backend, per
report from Zdenek.

Modified Files:
--------------
    src:
        controldata.c (r1.3 -> r1.4)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pg-migrator/src/controldata.c.diff?r1=1.3&r2=1.4)
        info.c (r1.6 -> r1.7)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pg-migrator/src/info.c.diff?r1=1.6&r2=1.7)
        pg_migrator.h (r1.12 -> r1.13)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pg-migrator/src/pg_migrator.h.diff?r1=1.12&r2=1.13)
        relfilenode.c (r1.10 -> r1.11)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pg-migrator/src/relfilenode.c.diff?r1=1.10&r2=1.11)