6.4.2: Fix the fix.

Well, that fix for a memory leak in 6.4.1 wasn't quite perfect. Yes, the memory got freed. But not in quite the right way for Windows, where you can't allocate memory in one DLL (in this case libpq) and free it in another (here, libpqxx). If you are using Windows, unescaping binary data in 6.4.1 will probably crash, and 6.4.2 should fix it. If you are not on Windows, or are not calling esc_raw, you shouldn't notice any difference.

Thanks @egorpugin for spotting the problem and pointing it out so quickly!