KWSys 2017-03-07 (5da8cfe0)

Code extracted from:

    https://gitlab.kitware.com/utils/kwsys.git

at commit 5da8cfe0544f95697808b0b46ed3183621902f0b (master).

Upstream Shortlog
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Ben Boeckel (1):
      c5529406 SystemTools: use std::string::empty

Robert Maynard (1):
      27e64d34 SystemInformation: Teach Is64Bits to check host architecture at runtime