get rhel7.3 selinux-policy-devel pkg for centos-7

Signed-off-by: Andrew Hsu <andrewhsu@docker.com>

contrib/builder/rpm/amd64/centos-7/Dockerfile

@@ -7,6 +7,7 @@ FROM centos:7
 RUN yum groupinstall -y "Development Tools"
 RUN yum -y swap -- remove systemd-container systemd-container-libs -- install systemd systemd-libs
 RUN yum install -y btrfs-progs-devel device-mapper-devel glibc-static libseccomp-devel libselinux-devel libtool-ltdl-devel pkgconfig selinux-policy selinux-policy-devel sqlite-devel systemd-devel tar git cmake vim-common
+RUN [ `rpm -q selinux-policy-devel | grep el7_3` ] || yum -y --enablerepo=cr install selinux-policy-devel
 
 ENV GO_VERSION 1.7.3
 RUN curl -fSL "https://golang.org/dl/go${GO_VERSION}.linux-amd64.tar.gz" | tar xzC /usr/local

contrib/builder/rpm/amd64/generate.sh

@@ -142,6 +142,10 @@ for version in "${versions[@]}"; do
 			packages=( "${packages[@]/pkgconfig/pkg-config}" )
 			echo "RUN ${installer} install -y ${packages[*]}" >> "$version/Dockerfile"
 			;;
+		centos:7)
+			echo "RUN ${installer} install -y ${packages[*]}" >> "$version/Dockerfile"
+			echo 'RUN [ `rpm -q selinux-policy-devel | grep el7_3` ] || yum -y --enablerepo=cr install selinux-policy-devel' >> "$version/Dockerfile"
+			;;
 		*)
 			echo "RUN ${installer} install -y ${packages[*]}" >> "$version/Dockerfile"
 			;;