Update to current packaging guidelines for systemd.

iguanaIR.spec

@@ -23,14 +23,13 @@ Requires:       udev
 BuildRequires:  cmake
 BuildRequires:  libusb1-devel, libusb-devel
 BuildRequires:  popt-devel
-BuildRequires:  systemd-units
+BuildRequires:  systemd
                 # For patch-soname (xxd, util-linux)
 Buildrequires:  /usr/bin/xxd
 BuildRequires:  util-linux
 
-Requires(post): systemd-units, systemd-sysv
-Requires(preun): systemd-units
-Requires(postun): systemd-units
+%{?systemd_requires}
+Requires(post): systemd-sysv
 
 # resolve cyclic dep iguanaIR <-> lirc. Once removed
 # in lirc, we can do the required so-bump.