sstables: summary: fix a bug when reading position

Since that whole entries array is memory mapped, we should not call
read_integer - which will byteswap it.

We should instead just fetch the position directly.

This was not spotted before because our test sstables tend to be relatively
small.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>

sstables/sstables.cc

@@ -504,7 +504,8 @@ future<> parse(random_access_reader& in, summary& s) {
                     auto keysize = entrysize - 8;
                     entry.key = bytes(reinterpret_cast<const int8_t*>(buf.get()), keysize);
                     buf.trim_front(keysize);
-                    read_integer(buf, entry.position);
+                    // FIXME: This is a le read. We should make this explicit
+                    entry.position = *(reinterpret_cast<const net::packed<uint64_t> *>(buf.get()));
 
                     return make_ready_future<>();
                 });