remove the old add_new_int and calls

last orrurences in syscalls replaced, 2 variants
- exit does not actually need the int
- all else, preallocate the int beforehand and in syscall assume the reg name (integer_tmp)

test missing

lib/mom/instruction/resolve_method.rb

@@ -58,7 +58,10 @@ module Mom
         branch  while_start_label
 
         add_code exit_label
-        Risc::Builtin::Object.emit_syscall( builder , :exit )
+        # temporary, need to raise really.
+        factory! << Parfait.object_space.get_factory_for(:Integer)
+        integer_tmp! << factory[:reserve]
+        Risc::Builtin::Object.emit_syscall( builder , :exit ) #uses integer_tmp
 
         add_code ok_label
         cache_entry[:cached_method] << callable_method