Comment 1 for bug 1715599

Trying to build without kio for example, without libxslt results in a build fail with:

-- The following REQUIRED packages have not been found:

 * LibXslt, <http://xmlsoft.org/XSLT>
   Required by the KDE help system to process DocBook XML

CMake Error at /usr/share/cmake-3.9/Modules/FeatureSummary.cmake:459 (message):
  feature_summary() Error: REQUIRED package(s) are missing, aborting CMake
  run.

Even in the latest libxslt git revision,

https://git.gnome.org/browse/libxslt/tree/libxslt/xsltlocale.h

#include <xlocale.h>

is required.