Memory manager flexibility for NUMA machines

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The provided lzham_set_memory_callbacks() is fairly nice for most uses 
(including to get around the need for malloc_usable_size() or _msize()).

Still, I'm locally patching the library to pass a custom "pUser_data" for every 
lzham_compress_memory() or lzham_decompress_memory() function call.

On NUMA machines, we typically want to allocate memory on the NUMA node that's 
appropriate for the thread doing the compression/decompression, and that 
requires a custom pUser_data (using thread-specific data is another option, but 
there's some serious overhead).

Thanks for this great library!

Original issue reported on code.google.com by alexis.n...@gmail.com on 28 Jun 2013 at 4:21