selinux: switch to conditional dependency

This ensures that the pcp-selinux package and all it's dependencies are
not pulled into containers and other systems that do not use SELinux.
https://fedoraproject.org/wiki/SELinux/IndependentPolicy#Adding_dependency_to_the_spec_file_of_corresponding_package

This rpm syntax is called "boolean dependencies" and is supported since rpm 4.13 (>= RHEL 8).
https://rpm-software-management.github.io/rpm/manual/boolean_dependencies.html

Co-authored-by: Vit Mojzis <vmojzis@redhat.com>
Resolves: rhbz#2050838

build/rpm/pcp.spec.in

@@ -220,9 +220,18 @@ fi
 }
 
 %if "@enable_selinux@" == "true"
+
+# rpm boolean dependencies are supported since RHEL 8
+%if 0%{?fedora} >= 35 || 0%{?rhel} >= 8
+# This ensures that the pcp-selinux package and all it's dependencies are not pulled
+# into containers and other systems that do not use SELinux
+Requires: (pcp-selinux = @package_version@ if selinux-policy-targeted)
+%else
 Requires: pcp-selinux = @package_version@
 %endif
 
+%endif
+
 Requires: pcp-libs = @package_version@
 
 %description

build/rpm/redhat.spec

@@ -286,9 +286,18 @@ BuildRequires: qt5-qtsvg-devel
 Requires: bash xz gawk sed grep findutils which %{_hostname_executable}
 Requires: pcp-libs = %{version}-%{release}
 %if !%{disable_selinux}
+
+# rpm boolean dependencies are supported since RHEL 8
+%if 0%{?fedora} >= 35 || 0%{?rhel} >= 8
+# This ensures that the pcp-selinux package and all it's dependencies are not pulled
+# into containers and other systems that do not use SELinux
+Requires: (pcp-selinux = %{version}-%{release} if selinux-policy-targeted)
+%else
 Requires: pcp-selinux = %{version}-%{release}
 %endif
 
+%endif
+
 %global _confdir        %{_sysconfdir}/pcp
 %global _logsdir        %{_localstatedir}/log/pcp
 %global _pmnsdir        %{_localstatedir}/lib/pcp/pmns