be more verbose when building sysconftool

Oddly, everything worked fine (before this commit) on my coreos host.
But on wercker host, the build failed with:

    error: Unable to open /rpmbuild/SPECS/sysconftool.spec: No such file or directory
    Bad spec: /rpmbuild/SPECS/sysconftool.spec
    No uninstalled build requires
    error: failed to stat /rpmbuild/SPECS/sysconftool.spec: No such file or directory
    2014/09/07 16:24:39 The command [/bin/sh -c /tmp/build_sysconftool.sh] returned a non-zero code: 1