Restructure copy implementation to avoid type-indexed block

wipforth.wat

@@ -542,20 +542,25 @@
        call $next)
 
  (func $copy (local $src i32) (local $dst i32) (local $n i32)
-       call $pop local.tee $dst
-       call $pop local.tee $src
-       call $pop local.tee $n
+       call $pop local.set $dst
+       call $pop local.set $src
+       call $pop local.set $n
 
-       block $done (param i32 i32 i32)
-         loop $loop (param i32 i32 i32) (result i32 i32 i32)
+       block $done
+         loop $loop
+           local.get $n
            i32.eqz br_if $done
+
+		   local.get $dst
+		   local.get $src
            i32.load8_u i32.store8
-           local.get $dst i32.const 1 i32.add local.tee $dst
-           local.get $src i32.const 1 i32.add local.tee $src
-           local.get $n   i32.const 1 i32.sub local.tee $n
+
+           local.get $dst i32.const 1 i32.add local.set $dst
+           local.get $src i32.const 1 i32.add local.set $src
+           local.get $n   i32.const 1 i32.sub local.set $n
+
            br $loop
          end
-         drop drop drop
        end
 
        call $next)