A better fix for 7e1bf2482d0bec220dc20de45427428193f96134; WT_ALIGN
"returns" a uintmax_t, which may or may not be the size of a size_t,
but is almost certainly not a uint32_t, and better gcc's than mine
complain.  WT_ALIGN isn't used in that many places, cast them all
explicitly.