- add tarval_top and tarval_bottom as alias for tarval_undefined and tarval_bad
- add tarval_top and tarval_bottom as alias for tarval_undefined and tarval_bad

[r20459]

killbug2004/libfirm,8l/libfirm,MatzeB/libfirm,libfirm/libfirm,8l/libfirm,libfirm/libfirm,8l/libfirm,MatzeB/libfirm,killbug2004/libfirm,jonashaag/libfirm,MatzeB/libfirm,jonashaag/libfirm,libfirm/libfirm,davidgiven/libfirm,davidgiven/libfirm,davidgiven/libfirm,killbug2004/libfirm,MatzeB/libfirm,jonashaag/libfirm,killbug2004/libfirm,davidgiven/libfirm,libfirm/libfirm,8l/libfirm,killbug2004/libfirm,killbug2004/libfirm,MatzeB/libfirm,libfirm/libfirm,jonashaag/libfirm,davidgiven/libfirm,killbug2004/libfirm,jonashaag/libfirm,MatzeB/libfirm,MatzeB/libfirm,davidgiven/libfirm,8l/libfirm,jonashaag/libfirm,jonashaag/libfirm,8l/libfirm,8l/libfirm,davidgiven/libfirm