Fixing tests for implicit return

previous commit affected rather many test, as the implicit returns add extra instructions
Also added some explicit returns, so as not to test the return logic too much. return (ie return nl) is a knonwn 3 risc operation.

test/mom/blocks/test_block_setup.rb

@@ -7,12 +7,12 @@ module Risc
     def setup
       super
       @input = as_block("return 5")
-      @expect = [LoadConstant, SlotToReg, RegToSlot, LoadConstant, SlotToReg, #4
+      @expect =  [LoadConstant, SlotToReg, RegToSlot, LoadConstant, SlotToReg, #4
                  RegToSlot, LoadConstant, LoadConstant, SlotToReg, SlotToReg, #9
                  RegToSlot, RegToSlot, RegToSlot, RegToSlot, SlotToReg, #14
                  SlotToReg, RegToSlot, SlotToReg, SlotToReg, SlotToReg, #19
                  SlotToReg, RegToSlot, LoadConstant, SlotToReg, RegToSlot, #24
-                 SlotToReg, FunctionCall, Label]
+                 SlotToReg, FunctionCall, Label] #29
     end
 
     def test_send_instructions