8bit immediates of Push are signed.
8bit immediates of Push are signed.

[r26616]

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