This converts the KWSys license to a pure 3-clause OSI-approved BSD
License. We drop the previous license clause requiring modified
versions to be plainly marked. We also update the KWSys copyright to
cover the full development time range.
The Compaq compiler (on VMS) includes 'String.c' in source files that
use the stl string while looking for template definitions. This was the
true cause of double-inclusion of the 'kwsysPrivate.h' header. We work
around the problem by conditionally compiling the entire source file on
a condition only true when really building the source.
The kwsysPrivate header double-inclusion check hits a false positive on
VMS for an undetermined reason. This simplifies the workaround and
documents it.
