Numerous local changes were made while vendoring Doug Lee's original
dlmalloc sources. Those changes basically boil down to:

  1. Fewer #ifdefs
  2. More modules (so linker can do a better job)
  3. Delete code we don't need (cf. Knight Capital)
  4. Readability / stylistic consistency

Since we haven't made any genuine improvements to Doug Lee's legendary
allocator, we feel this folder faithfully presents his intended work, in
harmony with Cosmopolitan conventions.

The only deleted code we're sure has compelling merit is the mspace
functionality. If we ever need memory pools, they might be more
appropriately vendored under //third_party/dlmalloc_mspace.