adding fake variables for export

shell-completion/zsh_completion

@@ -88,3 +88,6 @@ for comp_dir in $LHCB_COMPDIRS ; do
     esac
   done # loop over files
 done # loop over directories
+
+zstyle -s ':completion::complete:export:argument-rest:' fake-parameters preexisting
+zstyle ':completion::complete:export:argument-rest:' fake-parameters NINJAFLAGS CMAKEFLAGS ${preexisting}