d04047cc29bbc9d1f87a9346d1601e3dd87b6ca0 broken MSVC builds

[Mike Hommey]

Hi,

d04047cc29bbc9d1f87a9346d1601e3dd87b6ca0 makes rtree.exe assert:
<jemalloc>: z:\jemalloc-dev\include\jemalloc/internal/arena.h:553:
Failed assertion: "ret == small_size2bin_compute(size)"

Cheers,

Mike