Remove trapif and trapff (#5162)

This branch removes the trapif and trapff instructions, in favor of using an explicit comparison and trapnz. This moves us closer to removing iflags and fflags, but introduces the need to implement instructions like iadd_cout in the x64 and aarch64 backends.

cranelift/codegen/src/write.rs

@@ -489,12 +489,6 @@ pub fn write_operands(w: &mut dyn Write, dfg: &DataFlowGraph, inst: Inst) -> fmt
         } => write!(w, "{} {}, {}{}", flags, args[0], args[1], offset),
         Trap { code, .. } => write!(w, " {}", code),
         CondTrap { arg, code, .. } => write!(w, " {}, {}", arg, code),
-        IntCondTrap {
-            cond, arg, code, ..
-        } => write!(w, " {} {}, {}", cond, arg, code),
-        FloatCondTrap {
-            cond, arg, code, ..
-        } => write!(w, " {} {}, {}", cond, arg, code),
     }?;
 
     let mut sep = "  ; ";