(reload): Don't free scratch_list or scratch_block if 0.

From-SVN: r4925

gcc/reload1.c

@@ -2000,8 +2000,10 @@ reload (first, global, dumpfile)
   reg_equiv_constant = 0;
   reg_equiv_memory_loc = 0;
 
+  if (scratch_list)
     free (scratch_list);
   scratch_list = 0;
+  if (scratch_block)
     free (scratch_block);
   scratch_block = 0;