subject: Fix compiler warning introduced by previous commit
subject: Fix compiler warning introduced by previous commit

Sorry about that.  I need to figure out how to configure CMake to use
`-Werror=implicit-function-declaration` by default.

Conan-Kudo/libhif,rpm-software-management/libhif,edynox/libdnf,rpm-software-management/libdnf,hughsie/libhif,cgwalters/libhif,rpm-software-management/libhif,hughsie/libhif,cgwalters/libhif,edynox/libdnf,cgwalters/libhif,hughsie/libhif,rpm-software-management/libdnf,rpm-software-management/libhif,Conan-Kudo/libhif,Conan-Kudo/libhif,rpm-software-management/libdnf,edynox/libdnf,edynox/libdnf,hughsie/libhif,cgwalters/libhif,Conan-Kudo/libhif,rpm-software-management/libhif,rpm-software-management/libdnf