Simplified macros for systemd-powered distros.

rpm/SPECS/nginx.spec.in

diff --git a/rpm/SPECS/nginx.spec.in b/rpm/SPECS/nginx.spec.in
index e3e9b9d..af17d46 100644
--- a/rpm/SPECS/nginx.spec.in
+++ b/rpm/SPECS/nginx.spec.in
@@ -5,7 +5,14 @@
 %define nginx_loggroup adm
 
 # distribution specific definitions
-%define use_systemd (0%{?fedora} && 0%{?fedora} >= 18) || (0%{?rhel} && 0%{?rhel} >= 7) || (0%{?suse_version} >= 1315)
+%define use_systemd (0%{?rhel} >= 7 || 0%{?fedora} >= 19 || 0%{?suse_version} >= 1315 || 0%{?amzn} >= 2)
+
+%if %{use_systemd}
+BuildRequires: systemd
+Requires(post): systemd
+Requires(preun): systemd
+Requires(postun): systemd
+%endif
 
 %if 0%{?rhel} == 6
 %define _group System Environment/Daemons
@@ -22,8 +29,6 @@
 %define epoch 1
 Epoch: %{epoch}
 Requires(pre): shadow-utils
-Requires: systemd
-BuildRequires: systemd
 %define os_minor %(lsb_release -rs | cut -d '.' -f 2)
 %if %{os_minor} >= 4
 Requires: openssl >= 1.0.2
@@ -40,9 +45,7 @@
 %define _group Productivity/Networking/Web/Servers
 %define nginx_loggroup trusted
 Requires(pre): shadow
-Requires: systemd
 BuildRequires: libopenssl-devel
-BuildRequires: systemd
 %endif
 
 # end of distribution specific definitions