Haiku debug build, rdynamic flag unsupported.

Change default chunksize to 1MiB (microsoft#229)

This change makes the original 16MiB option not the common option.

It also changes the names of the defines to
  SNMALLOC_USE_LARGE_CHUNKS
  SNMALLOC_USE_SMALL_CHUNKS

The second should be set for Open Enclave configuration, and results in
256KiB chunk sizes.  The first being set builds the original 16MiB chunk
sizes.  If neither is set, then we default to 1MiB chunk sizes.

Fix sizeclass rounding error

Merge pull request microsoft#172 from microsoft/callback-fixes

Callback fixes

Addressing OE linking issues when built with GCC (microsoft#167)

* Use C++17 inline statics

This leads to better codegen in GCC, and fixes some linking issues in OE.

* Detect GCC and OE combination and fall-back to lock based ABA.

* clangformat

Merge pull request microsoft#102 from microsoft/cq-free

Code quality for `free`

Merge pull request microsoft#59 from plietar/paper

Add paper.

Merge pull request microsoft#21 from plietar/smart-next

Place the next pointer at a different place on every object.