Fix possible overflow when converting, possible negative number to uint16.
postingoff can be -1,when converts to uint16, overflow can raise.
Otherwise, truncation can be occurs, losing precision, from int (31 bits)
to uint16 (15 bits)
There is a little confusion in the parameters of some functions
On 2020-05-03 17:05:54 -0300, Ranier Vilela wrote:
> 1. Warning: the right operand to | always evaluates to 0
>
> src/include/storage/bufpage.h
> #define PAI_OVERWRITE (1 << 0)
> #define PAI_IS_HEAP (1 << 1)
>
> #define PageAddItem(page, item, size, offsetNumber, overwrite, is_heap) \
> PageAddI
