renamed type opcode to ir_opcode to not return may_alias if type check failed, proceed with next checks
renamed type opcode to ir_opcode
to not return may_alias if type check failed, proceed with next checks

[r8533]

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