support/testing/tests/package/test_tcl.py: new runtime test

Signed-off-by: Julien Olivain <ju.o@free.fr>
[Arnout: use f-string instead of string.format]
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>

support/testing/tests/package/test_tcl/rootfs-overlay/root/factorial.tcl

@@ -0,0 +1,11 @@
+#! /usr/bin/env tclsh
+
+proc factorial {n} {
+   set f 1
+   for {set i 1} {$i <= $n} {incr i} {
+      set f [expr {$f * $i}]
+   }
+   return $f
+}
+
+puts [factorial [lindex $argv 0]]