LV: Proper alignment of buffers for use with SIMD routines about libvisual HOT 5 OPEN

Or, do a byte-by-byte head and tail loop around the SIMD stuff that loops till it aligned the data (or went through it), we need this anyway for small data sets.

For example, if a data set only contains 5 bytes, aligned or not, we can't feed it to SSE or AVX. (I wouldn't write stuff in MMX nowadays), the routines we have remain valid of course.

Also: LIBOIL / ORC.

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We probably don't need SIMD for small data sets. The overhead associated with SIMD state saving/switching, and the fact that there's little data to compute makes the effort not really worth the trouble, I would think. Doing proper alignment is also quite a lot simpler than making routines account for any kind of starting address.

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Did a few more checks on the Intarwebz; it's basically guaranteed by glibc and VC++ that malloc() returns 8-byte and 16-byte aligned pointers on 32-bit and 64-bit systems respectively.

http://msdn.microsoft.com/en-us/library/ycsb6wwf.aspx
http://www.gnu.org/software/libc/manual/html_node/Aligned-Memory-Blocks.html

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In regards to small data sets: Indeed no SIMD is needed here, but I don't think that having _small and _large API calls is a bit awkward ;-).

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Added visual_mem_alloc_aligned() and visual_mem_free_aligned() in bcf3193

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