lib/tst_net.sh: fix tst_set_sysctl() for non-netns setup

When we don't use netns setup, $rparam is empty in tst_set_sysctl(),
and tst_net_run() mistakenly set sysctl command to $rparam. This results
to the following error, $cmd is empty:

  bbr01 1 TINFO: timeout per run is 0h 20m 0s
  bbr01 1 TINFO: emulate congestion with packet loss 0.5%
  bbr01 1 TINFO: compare 'cubic' and 'bbr' congestion alg. results
  bbr01 1 TINFO: setting cubic
  bbr01 1 TBROK: tst_net_run: command not defined

Fixes: 372d920 ("net: Add tst_net_run helper")

Signed-off-by: Alexey Kodanev <[email protected]>
[pvorel: quote -e to make obvious it's parameter for -r, not another parameter]
Acked-by: Petr Vorel <[email protected]>

Author: akodanev

testcases/lib/tst_net.sh

@@ -700,9 +700,9 @@ tst_set_sysctl()
 	[ "$3" = "safe" ] && safe="-s"
 
 	local rparam=
-	[ "$TST_USE_NETNS" = "yes" ] && rparam="-e"
+	[ "$TST_USE_NETNS" = "yes" ] && rparam="-r '-e'"
 
-	tst_net_run $safe -r $rparam "sysctl -q -w $name=$value"
+	tst_net_run $safe $rparam "sysctl -q -w $name=$value"
 }
 
 tst_cleanup_rhost()