[bugfix][RHEL/7] Fix make warning for RHEL7 builds

- Fixes #318
Merge pull request #325 from redhatrises/make_warning_rhel7

[bugfix][RHEL/7] Fix make warning for RHEL7 builds. See:
https://github.com/OpenSCAP/scap-security-guide/pull/325#issuecomment-64876450 for reasoning.