BRIN integer overflow

Greetings, everyone!

While analyzing output of Svace static analyzer [1] I've found a bug

Function bringetbitmap that is used in BRIN's IndexAmRoutine should
return an
int64 value, but the actual return value is int, since totalpages is int
and
totalpages * 10 is also int. This could lead to integer overflow

I suggest to change totalpages to be int64 to avoid potential overflow.
Also in all other "amgetbitmap functions" (such as hashgetbitmap,
gistgetbitmap,
gingetbitmap, blgetbitmap) the return value is of correct int64 type

The proposed patch is attached

[1] - https://svace.pages.ispras.ru/svace-website/en/

Oleg Tselebrovskiy, Postgres Pro