serv: use distro_vendor -i instead of virt detection

bin/serv

@@ -130,17 +130,11 @@ $(get_help HELPOPT)
 "
 }
 
-detect_virt()
-{
-        which systemd-detect-virt >/dev/null 2>/dev/null || return
-        a= systemd-detect-virt
-}
-
 print_version()
 {
         local on_text="(host system)"
-        local virt="$(detect_virt)"
-        [ "$virt" = "none" ] || [ "$virt" = "" ] || on_text="(under $virt)"
+        local virt="$($DISTRVENDOR -i)"
+        [ "$virt" = "(unknown)" ] || [ "$virt" = "(host system)" ] || on_text="(under $virt)"
         echo "Service manager version @VERSION@"
         echo "Running on $($DISTRVENDOR -e) $on_text with $SERVICETYPE"
         echo "Copyright (c) Etersoft 2012-2019"