add _hardened_build to older builds

libreoffice.spec

@@ -23,6 +23,8 @@
 # %%define source_url http://download.documentfoundation.org/libreoffice/src/%{libo_version}
 # URL for external projects' tarballs
 %define external_url http://dev-www.libreoffice.org/src/
+# default for f23 onwards
+%define _hardened_build 1
 
 # get english only and no-langpacks for a faster smoketest build
 # fedpkg compile/install/local/mockbuild does not handle --without ATM,