Build OVAL FTS only on UNIX systems
Build OVAL FTS only on UNIX systems

OVAL_FTS is strongly dependent on fts_read which is not available on
Windows, and it is used only in texfilecontent and file probe.
For textfilecontent probe we will need to do a special implementation
for Windows in future.

mpreisler/openscap,OpenSCAP/openscap,mpreisler/openscap,OpenSCAP/openscap,OpenSCAP/openscap,jan-cerny/openscap,redhatrises/openscap,jan-cerny/openscap,redhatrises/openscap,jan-cerny/openscap,OpenSCAP/openscap,OpenSCAP/openscap,redhatrises/openscap,redhatrises/openscap,mpreisler/openscap,mpreisler/openscap,redhatrises/openscap,jan-cerny/openscap,jan-cerny/openscap,mpreisler/openscap,OpenSCAP/openscap,jan-cerny/openscap,mpreisler/openscap,redhatrises/openscap