Widen lossy and exact page counters for Bitmap Heap Scan

Widen lossy and exact page counters for Bitmap Heap Scan

Both of these counters were using the "long" data type.  On MSVC that's
a 32-bit type.  On modern hardware, I was able to demonstrate that we can
wrap those counters with a query that only takes 15 minutes to run.

This issue may manifest itself either by not showing the values of the
counters because they've wrapped and are less than zero, resulting in
them being filtered by the > 0 checks in show_tidbitmap_info(), or bogus
numbers being displayed which are modulus 2^32 of the actual number.

Widen these counters to uint64.

Discussion: https://postgr.es/m/CAApHDvpS_97TU+jWPc=T83WPp7vJa1dTw3mojEtAVEZOWh9bjQ@mail.gmail.com