Make renice.test work without awk.

Also try to only kill processes we created.
diff --git a/tests/renice.test b/tests/renice.test
index e350c27..4f17d01 100755
--- a/tests/renice.test
+++ b/tests/renice.test
@@ -11,7 +11,7 @@
 {
   for each_proc in $@
   do
-    echo `awk '{ print $18 }' /proc/${each_proc}/stat`
+    echo `cut -d' ' -f18 /proc/${each_proc}/stat`
   done
 }
 
@@ -107,4 +107,4 @@
 done
 # Boundary test End
 
-killall yes >/dev/null 2>&1
+kill -9 $proc1 $proc2 $proc3 $proc4 $proc5