* Improve Arm64 support.

Make library compile and run on Arm64 8.2 (Nvidia Xavier arm+cuda)
`configure` is regenerated

* remove simd from utils.cpp

When data is being added to each index block, it needs to explicitly identify ids.

There we go

* Fix test_transfer_invlists.cpp

* Fix relative imports.

* Fix test_index_accuracy.py.

* Use default OSX version.

* Allow osx gcc6 build to fail.

* [c_api] minor tweak on Index_c header imports

* [c_api] Multi GPU constructs

- Add constructor & destructor for `FaissGpuMultipleClonerOptions`
- Add function `faiss_index_cpu_to_gpu_multiple`
- Add function `faiss_index_cpu_to_gpu_multiple_with_options`

* [c_api] fix doc comments in GpuClonerOptions

* [c_api] Improve cpu_to_gpu_multiple prototype

* [c_api] Improve cpu_to_gpu_multiple prototype

* [c_api] Add dtor definition for GpuMultipleClonerOptions

Add missing `\` in gpu Makefile

* Add GpuIndexBinaryFlat
* Add IndexBinaryHNSW

* Fix #558 - Make `d` an integer

* Use int()

Features:

- automatic tracking of C++ references in Python
- non-intel platforms supported -- some functions optimized for ARM
- override nprobe for concurrent searches
- support for floating-point quantizers in binary indexes
Bug fixes:

- no more segfaults in python (I know it's the same as the first feature but it's important!)
- fix GpuIndexIVFFlat issues for float32 with 64 / 128 dims
- fix sharding of flat indexes on GPU with index_cpu_to_gpu_multiple

os.tempnam is eliminated in python3.
Used tempfile.NamedTemporaryFile().name instead.
This is also valid for python2.7.

* Configure script use threaded MKL instead of sequential.

* Do not link against GNU OpenMP when linking against Intel OpenMP.

* Facebook sync

* Update swig wrappers.

* Fix comment.