reducing the label's int for return

placing the raw address in the register to jump to
puts the extra instruction at the risc level (not arm), thus changing a
lot of (brittle?) tests

lib/mom/instruction/return_sequence.rb

@@ -27,6 +27,7 @@ module Mom
       caller_index = Risc.resolve_to_index(:message , :caller)
       return_index = Risc.resolve_to_index(:message , :return_address)
       moves << Risc::SlotToReg.new(self, Risc.message_reg, return_index , return_address)
+      moves << Risc::SlotToReg.new( self , return_address , Parfait::Integer.integer_index , return_address)
       moves << Risc::SlotToReg.new(self, Risc.message_reg , caller_index , Risc.message_reg)
       moves << Risc::FunctionReturn.new(self, return_address)
     end

lib/risc/interpreter.rb

@@ -226,7 +226,7 @@ module Risc
     def execute_FunctionReturn
       link = get_register( @instruction.register )
       log.debug "Return to #{link}"
-      set_pc link.value
+      set_pc link
       false
     end