- add a macro to iterate over the Phi nodes of a block schedule only
- add a macro to iterate over the Phi nodes of a block schedule only

[r24055]

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