build: move file deleting action from %files list to %install

When building libvirt rpms on rhel5, I got the following error:

    File must begin with "/": rm
    File must begin with "/": -f
    File must begin with "/": $RPM_BUILD_ROOT/etc/sysctl.d/libvirtd
    Installed (but unpackaged) file(s) found:
   /etc/sysctl.d/libvirtd

It is triggerd by the %files list of libvirt daemon:

    %if 0%{?fedora} >= 14 || 0%{?rhel} >= 6
    %config(noreplace) %{_prefix}/lib/sysctl.d/libvirtd.conf
    %else
    rm -f $RPM_BUILD_ROOT%{_prefix}/lib/sysctl.d/libvirtd.conf
    %endif

After checking document of rpm spec file, I think it would be better
to move the file deleting line from %files list to %install script.

Bug introduced in commit a1fd56cb.

libvirt.spec.in

@@ -1420,6 +1420,10 @@ mv $RPM_BUILD_ROOT%{_datadir}/systemtap/tapset/libvirt_qemu_probes.stp \
 %endif
 %endif
 
+%if 0%{?fedora} < 14 && 0%{?rhel} < 6
+rm -f $RPM_BUILD_ROOT%{_prefix}/lib/sysctl.d/libvirtd.conf
+%endif
+
 %clean
 rm -fr %{buildroot}
 
@@ -1679,8 +1683,6 @@ fi
 %config(noreplace) %{_sysconfdir}/libvirt/libvirtd.conf
 %if 0%{?fedora} >= 14 || 0%{?rhel} >= 6
 %config(noreplace) %{_prefix}/lib/sysctl.d/libvirtd.conf
-%else
-rm -f $RPM_BUILD_ROOT%{_prefix}/lib/sysctl.d/libvirtd.conf
 %endif
 %dir %attr(0700, root, root) %{_localstatedir}/log/libvirt/qemu/
 %dir %attr(0700, root, root) %{_localstatedir}/log/libvirt/lxc/