Skip empty sysctl values
Skip empty sysctl values

We will skip empty values to be consistent with "sysctl" tool.
If this behavior will be considered a bug in "sysctl" tool,
we will need to revert this commit. See RHBZ #1473207.

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