added comments on VSX code path

which is still disabled for now.

Merge pull request Cyan4973#177 from Cyan4973/dev

v0.7.0

Merge pull request Cyan4973#166 from LambdAurora/dev

 Added export of public symbols on Windows.

Merge pull request Cyan4973#136 from Cyan4973/dev

xxHash v0.6.5

bump version 0.6.4

fixed minor ubsan warning

Merge pull request Cyan4973#81 from Cyan4973/dev

fixed minor conversion warnings

Merge pull request Cyan4973#71 from Cyan4973/dev

add `XXH*_copyState()` to list for `XXH_NAMESPACE`

Merge pull request Cyan4973#65 from Cyan4973/dev

updated API for static allocation

Merge pull request Cyan4973#58 from Cyan4973/dev

Dev