Add a trapff instruction.

This is the floating point equivalent of trapif: Trap when a given
condition is in the floating-point flags.

Define Intel encodings comparable to the trapif encodings.

lib/cretonne/meta/base/formats.py

@@ -75,6 +75,7 @@ RegFill = InstructionFormat(
 Trap = InstructionFormat(trapcode)
 CondTrap = InstructionFormat(VALUE, trapcode)
 IntCondTrap = InstructionFormat(intcc, VALUE, trapcode)
+FloatCondTrap = InstructionFormat(floatcc, VALUE, trapcode)
 
 # Finally extract the names of global variables in this module.
 InstructionFormat.extract_names(globals())