KWSys 2021-03-08 (5bfba5e1)

Code extracted from:

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

at commit 5bfba5e1a988e16df833e86062d61f4b70d83645 (master).

Upstream Shortlog
-----------------

Ben Boeckel (4):
      f69c5cb7 Directory: return a bool literal on Windows
      2a118b34 SystemTools: use nullptr in Windows-only code
      7ee0dbee Directory: capture the error message
      dd703ac6 SystemTools: make file copying mechanisms public

Sean McBride (1):
      3ba8a6de Glob: Change deleted ctor and operator= from private to public