Fixed bug in the sem-mov function

- This addresses issue 6 (http://code.google.com/p/gdsl-toolkit/issues/detail?id=6&can=1)

specifications/x86/x86-rreil-translator-m-z.ml

@@ -60,7 +60,7 @@ val sem-maskmovq x = sem-maskmov-opnd 8 x.opnd1 x.opnd2 x.opnd3
 val sem-mov avx-encoded x = do
   sz <- sizeof1 x.opnd1;
   a <- lval sz x.opnd1;
-  b <- rval sz x.opnd2;
+  b <- rvals Signed sz x.opnd2;
   write-extend avx-encoded sz a b
 end