Remove assorted dead code.

Assignments that are overwritten shortly afterwards and never used,
and a completely unused variable. Also, the bogus array access in
testbn.c could have actually accessed one beyond the array limit
(though of course it's only in a test harness).

testbn.c

@@ -82,8 +82,6 @@ int main(int argc, char **argv)
                 val = val * 16 + fromxdigit(start[i+1]);
                 *q++ = val;
             }
-
-            ptrs[ptrnum] = q;
         }
 
         if (!strcmp(buf, "mul")) {