examples: lang: Update examples to fix imports and port from yaml

Some small fixes that are useful for demos!

examples/lang/hysteresis1.mcl

@@ -1,10 +1,12 @@
+import "sys"
+
 file "/tmp/mgmt/systemload" {
 	content => template("load average: {{ .load }} threshold: {{ .threshold }}\n", $tmplvalues),
 }
 
 $tmplvalues = struct{load => $theload, threshold => $threshold,}
 
-$theload = structlookup(load(), "x1")
+$theload = structlookup(sys.load(), "x1")
 $threshold = 1.5	# change me if you like
 
 # simple hysteresis implementation