SC-nop-branch forwarding was fixed, with thanks to Rafael Soares

cMIPS/tests/ll_sc.expected

@@ -22,6 +22,9 @@ ffffffff
 ffffffff
 ok
 
+55555555
+ok
+
 ok
 
 ok

cMIPS/vhdl/core.vhd

@@ -988,6 +988,9 @@ begin
       elsif MM_is_MFC0 then          -- non-LW
         eq_fwd_A <= MM_cop0_val;
         rs_stall := FALSE;
+      elsif MM_is_SC then
+        eq_fwd_A <= x"00000000";
+        rs_stall := FALSE;         
       else
         eq_fwd_A <= MM_result;
         rs_stall := FALSE;
@@ -1013,6 +1016,9 @@ begin
       elsif MM_is_MFC0 then          -- non-LW
         eq_fwd_B <= MM_cop0_val;
         rt_stall := FALSE;
+      elsif MM_is_SC then
+        eq_fwd_B <= x"00000000";
+        rs_stall := FALSE;         
       else
         eq_fwd_B <= MM_result;
         rt_stall := FALSE;