Install _route completion only when route is available, remove unneeded $UNAME test.

contrib/net-tools

@@ -70,7 +70,7 @@ complete -F _mii_diag -o default mii-diag
 
 # Linux route(8) completion
 #
-[ $UNAME = Linux ] &&
+[ $UNAME = Linux ] && have route &&
 _route()
 {
     local cur prev
@@ -101,8 +101,8 @@ _route()
            echo "${COMPREPLY[@]}")
         ) )
     return 0
-}
-[ $UNAME = Linux ] && complete -F _route route
+} &&
+complete -F _route route
 
 # Local variables:
 # mode: shell-script