fix allocator corruption for large sizes#7338

Merged

Araq merged 3 commits intonim-lang:develfrom jcosborn:alloc1

Mar 17, 2018

+92-41

Commits on Mar 15, 2018

fix allocator corruption for large sizes
James
committed

Commits on Mar 16, 2018

allow large chunks to coalesce and added test case
James
committed

Commits on Mar 17, 2018

use correct constants in MaxBigChunkSize
jcosborn
committed