example showcase: use a more cross-platform friendly timer

tools/example_showcase.sh

@@ -1,15 +1,15 @@
 #!/bin/bash
 
 duration='2'
+function wait_seconds() { perl -e 'alarm shift; exec @ARGV' "$@"; }
 run_example() {
     cargo build --example $1
-    timeout "$duration" cargo run --example $1
+    wait_seconds "$duration" cargo run --example $1
 }
 
 example_list="$(cargo build --example 2>&1)"
 example_list=${example_list//$'\n'/}
 example_list="${example_list#error\: \"--example\" takes one argument.Available examples\: }"
-
 echo $example_list
 for example in $example_list
 do