MDEV-14560 Extra engines enabled through additional config are not loaded on first installation

Use RedHat-recommended /var/lib/rpm-state/mariadb/ for restart flag.
This also fixes SUSE where /var/lib/rpm-state doesn't necessarily exist.

cmake/cpack_rpm.cmake

@@ -81,7 +81,8 @@ SET(CPACK_RPM_SPEC_MORE_DEFINE "
 %define _bindir     ${INSTALL_BINDIRABS}
 %define _sbindir    ${INSTALL_SBINDIRABS}
 %define _sysconfdir ${INSTALL_SYSCONFDIR}
-%define restart_flag %{_localstatedir}/lib/rpm-state/mariadb-restart
+%define restart_flag_dir %{_localstatedir}/lib/rpm-state/mariadb
+%define restart_flag %{restart_flag_dir}/need-restart
 ")
 
 # this creative hack is described here: http://www.cmake.org/pipermail/cmake/2012-January/048416.html

support-files/rpm/plugin-postin.sh

 # request the server restart
+mkdir -p %{restart_flag_dir}
 echo > %{restart_flag}

support-files/rpm/server-postun.sh

 if [ $1 -ge 1 ]; then
   # request the server restart
+  mkdir -p %{restart_flag_dir}
   echo > %{restart_flag}
 fi